Battlekart Europe SA v Chaos Karts 1 Limited & Ors [2025] EWHC 1936 (IPEC)

[2025] EWHC 1936 (IPEC)Case No IP-2024-000061IN THE HIGH COURT OF JUSTICEBUSINESS AND PROPERTY COURTS OF ENGLAND AND WALESINTELLECUAL PROPERTY ENTERPRISE COURTVenue Royal Courts of Justice, Rolls Building, Fetter Lane, London, EC4A 1NLDate 25 July 2025
Before
HIS HONOUR JUDGE HACON
Between
BATTLEKART EUROPE SAClaimantCHAOS KARTS 1 LIMITEDDefendantsTHE ENTS INC LIMITEDDefendantLITTLE LION ENTERTAINMENT LIMITEDDefendantTHOMAS MAGUIREDefendant
Geoffrey Pritchard KC (instructed by Potter Clarkson LLP) for ClaimantDouglas Campbell KC and Antony Craggs (instructed by Shoosmiths LLP) for DefendantsHearing Hearing dates: 17-19 June 2025
Approved JudgmentThis judgment was handed down remotely at 10.45am on 25 July 2025 by circulation to the parties or their representatives by e-mail and by release to the National Archives..............................HIS HONOUR JUDGE HACON
[1]The idea of creating an altered experience of reality is probably as old as the idea of art. In recent years technology has led to the development of ever more convincing ways to deliver the impression of experiencing a different environment. Immersive experiences which engage the senses in this way have been developed in the fields of art, education, healthcare, marketing and not least, entertainment.[2]Video games became widespread before immersive experiences, including Nintendo’s Mario Kart,first marketed in 1992, in which players compete in go-kart races on screen. Players must negotiate the track and simulated obstacles such as rockets or bananas which affect the direction or speed of the kart – encountering a banana, for instance, will cause the on-screen kart to spin.[3]European Patent 3 304 522 B8 (‘the Patent’) claims a system for creating an immersive experience which combines driving a real go-kart with the features of a video game like Mario Kart. The player drives a kart around a track which takes the form of an image projected onto the floor. The track may be varied at any time and obstacles are projected onto it. The motion of the kart is partly within the control of the driver but is also significantly influenced remotely by the system. For instance it detects when the kart encounters a simulated obstacle and will cause the kart to react accordingly – using the same example, hitting a simulated banana will make the kart literally spin. There may be more than one driver so that drivers can compete. The combination of driving a real kart with the creation of these effects is called an extended reality or XR system.[4]The evidence sometimes also referred to augmented reality (AR), virtual reality (VR), mixed reality (MR) and immersive reality (IR) systems. IR is probably the broader term, encompassing XR, AR, VR and MR, although fashion in the use of those terms seems to come and go. To the extent that there are nuanced differences, they were not given any significance in the present case. For consistency I will use the term XR to mean any or all of the above.[5]The Patent is owned by the claimant (‘Battlekart’). The first to third defendants are related companies, all owned or ultimately owned by a holding company, Little Lion Holdings Ltd. The fourth defendant (‘Mr Maguire’) is a director of the First to Third Defendants and was treated at trial as if he is the moving force behind them. It was not necessary to decide whether that is accurate in law. For the most part the defendants need not be distinguished.[6]Battlekart has built up a franchising business for its Battlekart System. In 2017 Mr Maguire contacted Battlekart and there followed discussions about whether the third defendant would enter into a franchise agreement for the UK.[7]Later the defendants developed their own XR karting system, called the ‘Chaos Karts System’, first trialled in October 2020 and launched in London in 2021.[8]It is common ground that marketing the Chaos Kart System infringes claim 11 of the Patent as dependent on claims 1, 5 and 6, if valid. To avoid unnecessary repetition, hereafter my references to claim 11 should be taken to mean that claim as dependent on claims 1, 5 and 6.[9]The defendants have counterclaimed, alleging that claim 11 is invalid on the grounds of lack of inventive step, that claim 11 neither discloses nor renders plausible any technical contribution to the art, and added matter.

The Patent

[10]The title of the Patent is ‘System for creating an environment’. The specification is in French and there was an agreed translation.[11]This is Figure 2 which shows an embodiment of the invention:[12]Projectors 310 are in the ceiling of the room 900. A projection cone 611 emitted by each projector creates a partial image 610 on the floor 910 of the room. The partial images from the projectors combine to create an overall image, as shown a karting track 911. A ‘mobile element’ 200 as shown is a kart located on a projected track and for simplicity I will assume that the mobile element of the invention is a kart. There may be more than one kart.[13]There is a locating system comprising sensors 110 in the ceiling, each of which has a ‘capture zone’ 121, corresponding to the zone perceived by the sensor. The area of the floor within a capture zone is the capture surface 120 of the sensor. Preferably the capture surfaces cover the whole image 600 so that the kart is always visible to the locating system. An administrator uses a management device 500 to select the form of track and the type of game to be played. A server (not shown) receives this input and determines the information to be sent to the projection system and to the kart (or karts). In effect, the server coordinates the projection system, the locating system and the information sent to the kart.[14]Each kart has an emitter (not shown in Figure 2) so that its position may be detected by the locating system. The specification states (omitting reference numbers):
‘The emitter preferably comprises at least one electromagnetic radiation source, which can be an infrared lamp. The emitter more preferably comprises at least two electromagnetic radiation sources. Having two sources enables one of the sources to always be active in the event of the other one failing. The emitter even more preferably comprises a first infrared lamp 211 and a second infrared lamp.’
[15]The electromagnetic radiation is detected by the sensor, which allows each sensor to perceive karts present in its capture zone. Where the preferred infrared lamp or lamps are used by the emitter on the kart:
‘The sensor preferably comprises a filter, a camera and a data processing device. The filter is preferably a filter that lets the infrared pass through it. The camera is preferably a monochrome camera, capable of detecting the infrared radiation, and comprises, for example, a matrix of 128x96 pixels. The data processing device 115 is, for example, an FPGA.’
[16]An FPGA is a field-programmable gate array, a type of integrated circuit that can be reprogrammed after manufacture which allows flexibility of application by the user.

The claims

[17]These are claims 1, 5, 6 and 11 with claim 1 divided into 7 integers:
‘1A. System for creating an environment, the environment comprising at least one image arranged to be perceptible by at least one pilot of at least one mobile element, the system comprising: 1B. the at least one mobile element, which itself comprises an electronic interface and at least one actuating means connected to the electronic interface, and arranged to carry out a modification of characteristics of the mobile element based on a signal received from the electronic interface, 1C. a locating system arranged to determine a position of each mobile element present near the at least one image, and 1D. a server arranged to be connected to the electronic interface of each mobile element and to the locating system, the server being arranged to control said at least one actuating means based on the position of each mobile element received from the locating system, 1E. the system for creating an environment further comprising a projection system arranged to project the at least one image on at least one floor, 1F. the server being arranged to be connected to the projection system, the server is arranged to control the projection system based on the position of each mobile element received from the locating system, 1G. and in that each mobile element further comprises an emitter comprising at least two electromagnetic radiation sources comprising an infrared emitter, the emitter being arranged to transmit a signal enabling the mobile element to be located by the locating system. 5. System according to any one of the preceding claims, wherein the locating system comprises at least one microcontroller connected to the server and at least one sensor connected to the microcontroller. 6. A System according to the preceding claim, wherein each sensor comprises a camera arranged to take an image and capable of detecting infrared radiation. 11. System according to any one of the preceding claims, wherein the at least one mobile element is a kart, and the image comprises a karting track.’

The witnesses

[18]Battlekart had one witness of fact, the defendants two. Sébastien Millecam is the founder and a director of Battlekart. He is Belgian, has good English and did not seek to rely on an interpreter. One of the items of prior art relied on by the defendants was a prior disclosure by Battlekart itself about which he principally gave evidence.[19]Mr Millecam was criticised for being occasionally inaccurate in his witness statement and for attempting to suppress information about Battlekart’s prior disclosure from the Battlekart website. There may be something in this but I think that so far as it mattered Mr Millecam gave honest answers according to the best of his knowledge and recollection. He was a good witness.[20]The defendants’ first fact witness was Mr Maguire, the fourth defendant, who was only asked a few questions.[21]Another item of prior disclosure in issue was the ‘Live-Action RC Mario Kart’. This was a game created by three individuals who at the relevant time were students at the Massachusetts Institute of Technology (MIT). For a project which formed part of their course on software development, they created live version of the Mario Kart game using remote-controlled toy karts. One of the students was Nathaniel Rodman who provided a witness statement for the defendants. He was not cross-examined.[22]Battlekart’s expert witness was Warren Viant, Senior Lecturer and Deputy Head of School at the School of Computer Science at the University of Hull. The defendants’ expert was Gilray Densham. Mr Densham had a career in lighting for TV shows and then became the founder and former CEO of the CAST Group of Companies which develops software and lighting systems for live productions. The CAST Group manufactures and supplies, among other things, an infrared location system for use in amusement parks and immersive entertainments.[23]Mr Viant seemed in cross-examination to have retained a shaky grasp of the concept of common general knowledge (CGK). In re-examination he was asked to confirm a paragraph in his first report that identifies CGK, which he did. The concept is in fact better stated in a later paragraph in the same report, but even if he had confirmed that paragraph, the wording of which indicates that it was drafted by lawyers, the confirmation would not necessarily establish that Mr Viant had taken the concept of CGK fully on board.[24]There was an issue regarding how much Mr Viant knows about the sort of XR with which the Patent is concerned and the techniques used in such systems. Mr Viant has experience of XR systems such as plane cockpit simulators and has worked on projects such as XR software used to train radiation therapists. These are not the same as XR in the amusement and entertainment industries. Mr Densham expressed astonishment that Mr Viant did not know about matters which Mr Densham regarded as both important and clearly part of the CGK.[25]Possibly in an attempt to plug this gap, in examination-in-chief Mr Viant was asked about his students and what they had gone on to do after graduation. He said that the vast majority have gone into the fields of computer graphics, computer games and XR. Battlekart submitted that he will have talked to his former students and must have become more widely informed about XR. That may or may not be right, but it would not be evidence of Mr Viant’s first-hand knowledge. Without knowing in more detail what was said by whom to Mr Viant, it says nothing about his second-hand knowledge either.[26]A difficulty for both sides was a consequence of the parties each having a single expert. Keeping the number experts to the minimum was as it should be in this court but meant that it was going to be difficult to find an individual who has a sufficient background in each of the relevant disciplines. This should have been raised at the case management conference.[27]There was a project Mr Densham worked on that was given particular attention. It is a tracking system which locates moving items, such as the positions of actors on a stage or vehicles on a track. The system’s software coordinates these locations with lighting, sound, drones, lasers or other matters to generate appropriate effects at the right time and place for the production. The system is called ‘BlackTrax’. It was launched by the CAST Group in February 2012, around 3 years before the priority date. Mr Densham said that by 2013 BlackTrax was one of the industry standards as a tool for production and entertainment design. It has been widely used in live entertainment. Since before the priority date there have been similar systems available off the shelf. Mr Densham identified two others: Autopilot II and ZacTrack. He gave technical details about BlackTrax and about those two.[28]The system marketed by the defendants which is alleged to infringe the Patent is called ‘Chaos Karts’. It uses BlackTrax which plays a major role in making Chaos Karts work, providing it with a tracking system and software to coordinate it with a projection system and actuator control of the karts. Mr Densham knew this before giving his evidence. Battlekart submitted that this was highly significant hindsight which undermined the credibility of Mr Densham’s evidence on obviousness. I am not sure that it does. Mr Densham of course knows a great deal about the capabilities and potential applications of BlackTrax. It seems to me that if Battlekart’s point on hindsight were to be made good, it would have been necessary to pinpoint one or more aspects of the suitability of BlackTrax for a system such as that claimed in the Patent which could not have been predicted by Mr Densham without first knowing that BlackTrax has been successfully used in Chaos Karts. It would also have been necessary to investigate with Mr Densham the significance of any such matter regarding his views on inventive step. Neither was done.[29]Mr Densham was criticised for not engaging with the technical issues in the case and instead for the most part saying that they would be taken care of by BlackTrax. As I will discuss below, an important part of Battlekart’s case on CGK was that BlackTrax and similar tracking systems were not part of the CGK. If that is correct, some of Mr Densham’s evidence loses force. If it is not correct, Mr Densham gave technical details about these tracking systems. Assuming here that one or more of the three tracking systems was part of the CGK and that it would have occurred to the skilled team to use any of them, Mr Densham was entitled to assert, based on his technical explanation of how they work, that any of them would have made the implementation of a system as claimed in the Patent straightforward. He did make that assertion and of course it was open to Battlekart to challenge it, which was done. But it is not correct to say that Mr Densham failed to address the technical issues.

Person skilled in the art

[30]Two related points emerged that were significant to the outcome of this case. First, from which technical field(s) is the skilled person or team to be drawn? Secondly, which of Mr Viant and Mr Densham more closely embodied the skilled person or team and in consequence knew more about the CGK relevant to this case?

The Law

[31]A classic description of persons skilled in the art was given by Lord Diplock in Catnic Components Limited v Hill & Smith Limited [1982] RPC 183, at 242, namely: ‘those likely to have a practical interest in the subject matter of [the patentee’s] invention’.[32]Lord Diplock’s characterisation may sometimes be unsatisfactory when considering inventive step. The assumption that the skilled team has a practical interest in the subject-matter of the invention can, on certain facts, broaden the scope of CGK held by the team in a manner which unfairly prejudices the patentee.[33]This was not a point that the House of Lords had to consider in Catnic. In Schlumberger Holdings Ltd v Electromagnetic Geoservices AS [2010] EWCA Civ 819, Jacob LJ pointed out that Catnic was concerned with the scope of the claims in suit, not inventive step (at [38]).[34]The potential unfairness to the patentee arises where the invention claimed relates to a problem which existed in a first technical field at the priority date; the patentee says that the problem is solved by the application of a concept drawn from a second, technically remote field. Technically remote here means that the CGK of a skilled person the first field does not closely overlap the CGK of a skilled person from the second field – the more remote the fields, the less overlap there will be.[35]Those were the facts in Schlumberger. The Court of Appeal ruled that in consequence the composition of the skilled team through whose eyes inventive step was to be assessed should be different from the composition of the skilled team assessing, for instance, insufficiency, where the team’s knowledge of the invention is required, see Schlumberger at [22] to [70].[36]Jacob LJ went on to explain how inventive step must be approached in such circumstances:
‘[71] It follows that the correct approach in this case is to start with the real problem faced by exploration geophysicists. Did they appreciate they had a solvable problem?. How could they determine whether a thin layer of porous rock identified by seismics as potentially hydrocarbon bearing in fact does so or is just a false positive bearing only brine or water? One then asks whether the notional exploration geophysicist who read the cited prior art would see that the answer was to use CSEM, or if not that, at least that CSEM had a sufficient prospect of being useful that it was worth asking a CSEM expert. [72] The problem must also be approached the other way round, from the point of view of the CSEM expert. Would he or she know of the exploration geophysicists' problem and, if so, would he or she appreciate that CSEM had a real prospect of being useful to solve the problem? [73] In short: was the marriage obvious to either notional partner? [74] One further approach is not necessary: that is to ask whether the notional team including both types of expert would see that CSEM would solve or stood a very good chance, of solving the problem. That is because Mr Thorley's concession provides the answer here. [75] There is danger to be avoided. There are cases where, even though you can, in retrospect, clearly see that there was a problem and articulate what it was, workers at the time did not do that. They did not say: “this is our problem. If only we had a solution to it.” Instead they simply put up with things as they were. Then the essence of the invention is the insight that there was a solvable problem at all. Haberman v Jackel International Ltd, see below, is a good example.’
[37]When Jacob LJ said at [72] that the problem ‘must’ also be approached the other way around, presumably he meant that one or other, or optionally both analyses must be adopted.[38]So in a case like Schlumberger the first possibility is that inventive step falls to be assessed from the perspective of the skilled team drawn from the field of the problem: at the priority date would such a team have contemplated solving the problem by using the relevant concept drawn from the remote field of the solution? Alternatively, would the relevant concept been seen by the team as having a sufficient prospect of being useful that an expert in the field of the solution should be consulted?[39]The second possibility is that inventive step is assessed from the perspective of a skilled team from the field of the solution. At the priority date would a skilled team from the field of the solution have contemplated applying the relevant concept used in that field to a project in the field of the problem, specifically to solve the problem in question? Or at least would it have been considered worthwhile to consult a person with expertise from the field of the problem?[40]If the answer to either question is yes, the invention is likely to lack inventive step. If the answer to both is no, there is an inventive step.[41]This is jumping ahead to inventive step. The more immediate point is that in a case like Schlumberger, for the purpose of assessing inventive step the skilled team may come from either the field of the problem or the field from which the concept of the solution is drawn. Either way, it is not a Catnic team.[42]In most instances the Catnic formulation works perfectly well and identifies the same skilled person or team for all purposes, see Schlumberger at [40] and Medimmune Ltd v Novartis Pharmaceuticals UK Ltd [2012] EWCA Civ 1234, at [72]. A Catnic team makes life simpler, but where there is doubt that such a team is appropriate for inventive step, the Schlumberger approach is to be taken.[43]In Illumina Cambridge Limited v Latvia MGI Tech Sia [2021] EWHC 1026 (Pat) Birss J proposed the following steps in such a case (at [68]):
‘(i) to start by asking what problem the invention aimed to solve; (ii) to consider what the established field which existed was, in which the problem in fact could be located; and (iii) it was the notional person or team in that established field which was the relevant team making up the person skilled in the art.’
[44]As indicated in Schlumberger, there is also nothing wrong with considering instead the established field from which the solution to the problem is taken and assessing inventive step from the perspective of a person or team in that field, although this may require the citation of different prior art. Or both can be done as alternatives.[45]The reference in Illumina to an ‘established’ field is a reminder of a related principle of law: any field of problem team or field of solution team must come from a technical field known to have existed at the priority date, see Schlumberger at [42] and Medimmune at [76]. Neither may be from a technical field which did not then exist.[46]Taking the example of beginning with a field of problem team, such a starting team is to be identified as described in Illumina. It is a starting team because that is not necessarily the end of the process for identifying the final hypothetical skilled team.[47]It is to be expected in such a case that cited prior art will come from the field of the solution. As Jacob LJ indicated in Schlumberger, the team from the field of the problem is deemed to have read each cited item of prior art and the court must decide whether such a team would then either have(a) perceived the invention or(b) decided that the concept disclosed in the prior art had a sufficient prospect of being useful such that it was worth consulting an expert in the field from which it was drawn.[48]The hypothesis is that the skilled team will read each item of cited prior art with care and interest, no matter how remote the field from which comes. If (b) is applicable, the skilled team may expand to include an expert from the second field. This could be viewed as the original team consulting someone else without formally expanding the team. It makes no difference – in effect, there is an expanded team which will probably no longer collectively come from an established field.[49]There is a procedural aspect to this. In such a case the evidence presented at trial will have to be prepared in successive stages. First, there will be evidence from an expert from the field of the problem. Without knowledge of the patent in suit but with access to the cited prior art, that expert must initially consider whether a skilled person from the field of the problem, having read the prior art with care and interest, would either have contemplated the invention or alternatively would have taken the view that the prior art discloses information which has a sufficient prospect of being useful that it would have been worthwhile consulting someone from the field of the prior art, i.e. the field of the solution. The expert’s evidence on this is of course recorded. If it is his or her belief that the skilled person would have thought it worthwhile to consult someone from the field of the prior art, an expert from this second field will then discuss the matter with the first expert. Preparation of evidence from the experts on the likely views of the combined hypothetical skilled team will subsequently go forward in the usual way.[50]If the foregoing procedure is adopted, expert evidence as to whether the starting skilled person or team would have consulted someone from outside their established field ought not to be vulnerable to hindsight. Even so, such evidence and the reasons given in support of it will be considered with appropriate care.[51]Thus, for the purpose of assessing inventive step, there may be a Catnic team, or alternatively the assessment starts with a field of problem team or a field of solution team. Usually, a Catnic team will be suited to the task and it will be more efficient for all concerned if that single team is used for inventive step and anything else that falls to be considered by the skilled team. Occasionally, a field of problem team or a field of solution team will be required as the starting team for inventive step. In principle both could be used, subject to the permission of the court.[52]A party seeking to rely on a field of problem team or a field of solution team should plead their case accordingly, This will give the opposing party the opportunity to file evidence to deal with that approach at the trial, or alternatively to challenge the approach if it is appropriate to do so. The pleading will also provide justification (particularly in this court) for each side to seek to call more than one expert.

The skilled team in this case

[53]The Patent discusses the prior art and provides a guide to the field of the problem in the present case:
‘Current karting systems comprise a track marked on the floor and karts which drive on this track. Unfortunately, the track is materialised on the floor by stationary elements, which take a long time to install and a long time to remove, like paint or stickers. It is therefore not possible to quickly change track in a given place. Furthermore, karts can collide with each other or with stationary objects. Furthermore, the karting race is fun but repetitive, and karting in one single kart is barely any fun. The invention therefore aims to propose a system for creating an environment which enables the implementation of a karting system which has none of these problems.’
[54]The reader of the Patent is there told that conventional karting is fun but has the stated disadvantages which the invention aims to solve. It implies that the starting point, the technical field of the problem, is the field of conventional karting. As appears later from the specification, the solution is said to lie in using techniques such as projector and locations systems and using software which controls them. All of these were known and exploited in the immersive entertainment industry, which could be seen as a technical field remote from conventional karting.[55]Mr Viant, Battlekart’s expert, said:
‘35. The Patent could have been of interest to readers in related industries. However, there are significant differences between each of these industries and the Patent. In my opinion, the closest related industries to the field of the Patent would have been: 35.1. The karting industry, i.e. companies specialising in making and operating karts and karting tracks. The Patent is a development from traditional karting systems. However, the Patent adds specialised technology from other fields which would have been wholly unfamiliar to the karting industry. 35.2. The video game industry. The use of a server to implement a virtual world interactable by players is clearly similar to a computer game. At the Relevant Date, the video game industry was interested in AR gaming, and some consoles and peripherals such as the Xbox Kinect had motion tracking capability. However, the video game industry did not design systems at the same scale as the Patent, with players generally viewing games through a computer screen and interacting with them in small spaces whether through a controller or other means such as hand gestures. 36. In summary, the Patent is too technologically sophisticated to be of interest to the karting industry, and too large-scale to be of interest to the video game industry.’
[56]It seems that in Mr Viant’s opinion the Patent would have been of practical interest to no one, which is not altogether helpful. Such an opinion may have had its origin in the idea of setting up an argument that this is a Schlumberger type case, as pursued in submissions. Mr Viant continued:
‘38. A skilled team would be required to carry out the teaching of the Patent. The skilled team must however be realistic. As I will explain below, MR karting systems similar to the BK system did not exist at the Relevant Date, and hence there was no industry which specialised in designing such systems. … the skilled team would have to be comprised of generalists with knowledge across their field of technology and some practical experience, rather than specialists with detailed expertise in narrow areas. The members of the skilled team would likely come from the karting or gaming industry, as described above.’
[57]Despite what Mr Viant had said earlier, apparently he was instructed that in law the skilled team had the collective CGK to implement the invention using the information contained in the Patent: a Catnic team. There was no single field from which a skilled person could be drawn so there would have been a team drawn from different fields.[58]Mr Viant went on to say that the team would be led by a systems engineer. Additional necessary expertise would be provided by a software developer having practical experience of the gaming industry and also a hardware engineer who would design or modify karts to make them suitable for use in an XR karting system. He added:
‘[The team’s] work sits between the hardware engineer and software developer, requiring the systems engineer to have a good overview of the entire project and all the subsystems within it.’
[59]Since Battlekart apparently had a plan to press for a Schlumberger approach to the present case, as counsel’s submissions implied, it would have required evidence from an individual drawn from their chosen field, the field of the problem, i.e. conventional karting. Mr Viant was not the man for that job.[60]Mr Densham for the defendants said:
‘27. Shoosmiths has explained to me that the skilled addressee (sometimes referred to as the person skilled in the art or skilled person), is the individual or team who is likely to have a practical interest in the subject matter of the relevant patent as at the priority date and has practical knowledge and experience of the kind of work in which the invention is intended to be used. Shoosmiths has explained that he/she/they are deemed to have specific attributes. In particular, they are deemed to have the common general knowledge of those working in the field to which the patent relates but have no inventive capacity. 28. Given the problem posed by the patent, as at the priority date the skilled addressee is likely to be a team in the amusement park or immersive entertainment industry. …’
[61]Mr Densham’s paragraph 27 is consistent with a Catnic approach to finding the relevant skilled team. His paragraph 28 seems to go instead for a field of problem team which he identifies as the field of the amusement or immersive entertainments industry, giving no reason why this is the correct field although it is close to his own field of experience. He did not say that he had been advised by lawyers that it was legitimate to approach inventive step from the perspective of a skilled person in the field of the solution. Nor did he express the view that having read the prior art, he believed that this would have been the amusement or immersive entertainments industry and that he did not believe that a skilled person would have thought it worthwhile to consult anyone else.[62]In submissions counsel for both Battlekart and the defendants cited Illumina as setting out the correct approach to identifying the skilled term for inventive step – a field of problem team.In fact, Battlekart emphasised the danger of going outside the perspective of the field of problem team when considering inventive step.[63]In his second report Mr Densham, possibly reflecting a tactical shift by the defendants, agreed with Mr Viant’s final characterisation of the skilled team. It is on any view a Catnic team.[64]Not only that, at least by the time of his second report Mr Densham raised no difficulty with the further details suggested by Mr Viant. They were:(1) The systems engineer would have ‘practical experience in location tracking systems, projection systems, and embedded and integrated systems’.(2) The software engineer would have ‘knowledge of computer graphics, computer simulation, distributed architectures (i.e. software running across multiple connected hardware devices) and location tracking algorithms, and likely with practical experience of the gaming industry’.(3) The hardware engineer would have the ability to ‘design or modify karts to make them suitable for use in an XR karting system’ and experience of ‘other hardware components, so that they can assist the systems engineer to bring together the different components of the hardware and software to form a functional commercial product’.[65]I must go with the evidence. The skilled team is a Catnic team with the characteristics set out in the preceding paragraph.

Which of the experts was closer to the skilled team?

[66]Having read the prior art, the skilled team as identified would have had in mind what, if anything, could be done to improve the experience of conventional karting by using features of the prior art. At the forefront of the team’s collective mind would have been that if features of the cited prior art were to have any practical application to conventional karting there would be a need to have a system capable of maintaining continuous location of the karts, a need to use lighting to project images of a track and of obstacles and possibly other items, and a need to have software which would coordinate these to make a satisfying karting experience. Skills in tracking and lighting are skills found in the entertainment industry.[67]Battlekart’s position was that Mr Viant had the background to speak with authority about the systems engineer who would be the key figure pulling the project together, having been advised on details of software implementation by the software engineer and on how to adapt commercial karts so that they would respond as required to electronic instruction from the server as well as from the player/driver. That may be right, but this case raised issues about the CGK of other members of the Catnic skilled team. This included the CGK relating to a tracking system which can detect the location of each kart and CGK relating to a projector system capable of producing images which combined to create, among other things, an image of the track and obstacles on it. These were important issues about which the experts gave evidence. Apparently Mr Viant does not have first-hand knowledge and experience of either of the two I have just mentioned.[68]Mr Densham’s background is in lighting for TV, theatrical and outdoor productions, but not directly XR. He founded his CAST company and led the development of software to control lighting for the creation of effects in live productions and to coordinate the lighting with a tracking system. The considerations that would have occurred to the skilled team having read the prior art are significantly more within Mr Densham’s area of expertise than Mr Viant’s.[69]Neither Mr Viant nor Mr Densham embodied the Catnic skilled team of this case but Mr Densham by some margin came closer.

The common general knowledge in this case

[70]Mr Viant identified the invention of the Patent as combining four elements:(i) specially adapted karts,(ii) a locating system for tracking the karts (often referred to in the evidence as a tracking system),(iii) a server to implement the game engine (i.e. to interact with and coordinate the tracking system, the projectors and the driving instruction of the player such that XR karting can be experienced by the player, which depends on the server’s software) and(iv) a visualisation system for allowing the kart pilots to see the game world (i.e. a projection system). He said that there were commercially available options for all the elements of the invention and that each of these options was part of the CGK. This was common ground.

BlackTrax

[71]The principal disagreement between the parties regarding the CGK was whether BlackTrax or an equivalent system on the market at the priority date would have formed part of the skilled team’s CGK.[72]Battlekart’s foremost point was that Mr Viant had never heard of any of these systems. This does not come as a surprise. Mr Viant has no experience in the sort of tracking, lighting and software coordination needed for live entertainments. His world of XR has been confined to simulated experiences in an aircraft cockpit or in a medical context. He said that he knows about video games but admitted that he has never created one. He has no experience of amusement parks or the immersive entertainment industry outside his knowledge of video games. None of the projects Mr Viant has been involved in would have engaged any interest in a system like BlackTrax. Mr Viant’s lack of knowledge of BlackTrax and equivalent tools does not rule out their being part of the CGK.[73]Mr Densham, of course, is very familiar indeed with BlackTrax and to a large though lesser extent, equivalent systems. It does not follow that any of them would have formed part of the skilled team’s CGK. But such systems would undoubtedly have been useful to a skilled team with knowledge of the problems of projected lighting, tracking and coordinating software. On the evidence I have, Mr Densham is likely to have the more reliable idea of whether the skilled team would have known about any of the three tracking systems, especially BlackTrax.[74]Battlekart said that BlackTrax only became available three years before the priority date. That gets Battlekart nowhere without evidence that in those three years it was a niche product known to few. This was not Mr Densham’s evidence.[75]Battlekart pointed out that Mr Densham did not state the number of sales of BlackTrax or equivalent systems or to whom the systems were advertised. That is correct but Mr Densham’s evidence in chief was that the systems formed part of the relevant CGK as he understood that to be. He fully maintained this in cross-examination and was not shown to have misunderstood the meaning of CGK in law.[76]Mr Viant was asked about the following passage in Mr Densham’s second report:
‘Put simply, by 2015, if any amusement park developer or live entertainment producer wanted location tracking they knew, without doubt of the options available to them and, in particular, BlackTrax (including the United Kingdom).’
[77]Mr Viant said that he had absolutely no reason to dispute that passage.[78]Battlekart submitted that even if BlackTrax and equivalent systems were known by the skilled team to exist, the evidence did not show that the team would have appreciated that such a system could be used to improve the experience of conventional karting. Reasons for this assertion were given.[79]The first was that the evidence did not show any use of BlackTrax outside the entertainment industry save for one instance if its use at the opening of the Rotterdam container terminal.[80]The hypothesis as I have found it to be is that the skilled team, with its CGK as discussed above was contemplating improvements to the experience of conventional karting. The prior art, which I will come to, would have led the team to consider the sort of lighting projection, tracking and coordination that is used in the entertainment industry These are made simpler for anyone in that industry by BlackTrax and similar systems. As indicated above, Mr Viant did not dispute that any park developer or live entertainment producer in the UK would have known about BlackTrax.[81]Mr Densham accepted that apart from the use of BlackTrax in Rotterdam and an example of its use to track motorbikes in a show, both before the priority date, there had been no public demonstration of using BlackTrax to track moving objects travelling at up to 30mph. Battlekart submitted that in neither case was there a driver of a moving object who was given partial control of the moving object.[82]That is correct, although Mr Densham’s examples showed that BlackTrax could probably be used to track karts driven by players around a track, at the least up to an unknown speed. The skilled team would have known that BlackTrax may or may not have provided the whole solution to the task prompted by the prior art but even if not, it would have been of considerable assistance and there was no reason to dismiss the use of BlackTrax on that ground.[83]I find that the skilled team would not only have known about BlackTrax and the two equivalent tracking systems at the priority date, the team would also have believed that any one of them would prove a useful tool in the task of improving a karting experience. The team would have tried using a tracking system of that kind expecting it to be helpful.

The prior art

[84]In support of their case on lack of inventive step, the defendants relied on two alleged prior disclosures and one item of written prior art:(1) The Battlekart Disclosure. This was a demonstration by Battlekart of the Battlekart system conducted in Mons before the priority date. Various documents and videos are relied on to demonstrate the detail of what was disclosed.(2) The MIT Disclosure. This was a demonstration of a game based on Mario Kart created by three students at MIT evidenced by a document and videos.(3) The Disney Application. This is US patent application no. 2010/0144413 entitled ‘System and method for providing a real-time interactive surface’ owned by Disney Enterprises, Inc.

Inventive step

[85]I discussed the law on alleged prior disclosure in Claydon Yield-O-Meter Limited v Mzuri Limited [2021] EWHC 1007 (IPEC), at [69]-[81]. The following principles apply:
‘[72] It was common ground in this case that in a prior user case in which it is said that the invention was made available to the public, even though nobody in fact took advantage of that availability, the information made available is that which would have been either noticed or inferred by a person skilled in the art who, hypothetically, had taken advantage of the access to the invention established on the evidence. I agree. In effect, the hypothesis concerns a skilled person as observer. [73] Mr Nicholson made the further point that for the invention to be enabled, the skilled person need only have been able to discern details of the invention at the level of generality at which they appear in the claim. I agree. [74] As appears from Folding Attic Stairs [Folding Attic Stairs Ltd v Loft Stairs Co Ltd [2009] EWHC 1221 (Pat)] it must be assumed that the skilled person’s access was limited to that permitted in law; access by trespassing, for instance, is excluded from the hypothesis.’
[86]There was no dispute between the parties regarding the general principles of law applied to inventive step.

The Battlekart Disclosure

[87]In law, the information disclosed at the Battlekart Disclosure was that which a member of the public attending the event in Mons could have seen. No issue arose as to whether it should be assumed that any sort of technology would have been used by such a person during their observations. The issue was what would have been seen by the naked eye. The defendants relied on 5 videos shot on various dates to evidence what an attendee would have seen. It was accepted by Battlekart that the five videos provided such evidence.[88]Battlekart pleaded that the following integers of claim 11 were neither disclosed nor made obvious by the Battlekart Disclosure. The integers are set out in full above and are here summarised:(i) Integer 1(C). The locating system used to track the karts. In evidence it was referred to as a ‘tracking system’.(ii) Integer 1(F). A server with software that coordinates image projection with the location of the kart.(iii) Integer 1(G). Each kart has an emitter which transmits a signal enabling the tracking system to locate the kart, the emitter comprising at least two electromagnetic radiation sources, at least one of which is an infrared (IR) emitter.(iv) Integer 5(A). The overall system has at least one microcontroller connected to the server and at least one sensor connected to the microcontroller.(v) Integer 6(A). The sensor has a camera arranged to take an image capable of detecting IR radiation.[89]Battlekart argued that the Battlekart Disclosure would not have enabled the skilled team to build a system as claimed.[90]The skilled team included a systems engineer with practical experience in location tracking systems and a software engineer with knowledge of location tracking algorithms. The question on enablement was whether there is any information provided in the Patent which is lacking in the CGK and if so, whether that lack of information would have meant that the skilled team could not have created a system covered by claim 11.[91]In his first expert report Mr Viant largely endorsed Battlekart’s pleaded case but, presumably in respect of integer 1(F), he said that the Battlekart Disclosure does not disclose ‘a distributed-rending projection system’, words that do not appear anywhere in claim 11. He did not say that there was no disclosure of a server that coordinates image projection and the location of the kart. Battlekart’s pleading did not dispute that a projection system within the meaning of integer 1(E) was disclosed in Mons.[92]With regard to information said to be in the Patent but not the CGK, my attention was drawn to what Mr Viant had said in re-examination. He referred to Figure 5:[93]Figure 5 shows the components of the projection system. Mr Viant explained what it tells the reader:
‘A. It tells the reader there is overlapping and there is blending, yes. Those are known, within inside video creation, those are known terms, blending, overlapping. There are a number of algorithms associated with that to try to achieve. It is really on a case by case basis.’
[94]Mr Viant expanded on this:
‘A. Figure 5 tells you that it is using blending, which is the process required to achieve that perfect calibration -- sorry, to achieve the image. What it does not do is it does not tell you which blending algorithm it is using. You would then have to find appropriate ones. Those require a level of knowledge that is not -- that is where in my mind the inventive step comes into finding an appropriate one for this particular use case. It may be that this use case is so common to another use case that inventive step is not required. In most of these they are bespoke. So, if I was creating a system like this, it would not be obvious immediately, certainly not under the common general knowledge definition, what that blending process, the one to use, would be. So it teaches you that I have to use a blending process, but then I would have to go out and experiment to find an appropriate blending process. It does not mean that it is impossible to find one. It means that I would just have to experiment until I found one that was appropriate, coupled with, the back of this is the context you are setting this in, it is a commercial system that needs to be easily maintained. So you may find a perfect blending solution, but it may be really difficult to maintain it or impossible given the vibrations of the room or whatever else. It is the case of finding one that is an appropriate trade off between quality and usability.’
[95]I understand blending to be the combining of multiple projected images into a coherent single image. No point was raised about what seems to have been a self-evident need for blending if the skilled team is using more than one projector. Mr Viant’s evidence came down to saying that the known idea of blending was represented in Figure 5 but the reader of the Patent would have had to conduct what may have been difficult experiments to find the right algorithm to achieve satisfactory blending in practice.[96]The Patent does not tell the reader what the right algorithm is, guide the reader thorough the difficult experiments or otherwise tell the reader how to get the right algorithm. Since the skilled team is a Catnic team and there is no pleading of insufficiency, I must conclude that the team would have been able to find a suitable algorithm by applying their CGK. There can have been no inventive step involved in doing so.[97]I note that it appears to have been Mr Viant’s view that the inventive step in the whole endeavour recorded in the Patent was to do with finding the right algorithm, although I cannot be sure from an answer in re-examination. But if that is right, the invention of claim 11 does not embody an inventive step.[98]Also and aside from anything else, claim 11 covers a system in which just one image is projected. Blending successfully is not part of the claimed invention.[99]As the re-examination continued Mr Viant was specifically asked about his term ‘distributed rendering’. He referred to Figure 7 which also shows the projection system:[100]Mr Viant said that distributed rendering was described in the passage of the Patent which explained Figure 7, although not referred to by that name. In its written closing submissions Battlekart placed reliance on this part of the re-examination in support of its contention that the Patent disclosed information which was not part of the CGK. This is the relevant passage:
‘Q. Just remind His Honour why you say that tells you that this is talking about distributed rendering? A. It mentions the fact that you have a server and then you were talking about sending multiple images, sorry, sending the data to the video stream devices, which it explains are then -- there was a section in here talking about them being raspberry pies. Therefore, it is not a bespoke piece of hardware that is determining having a video signal coming into it and all it is doing is sending it out to a projector. It explains here the fact that the data -- the easiest way of describing it is it is not a movie being played from the server through a device on to a projector. That would not be my classification of distributed rendering. All you are doing is effectively it is a glorified cable. This has a unit in between, multiple units, these raspberry pies or mobile devices that it describes in the patent, that take an image from the sever, but most importantly -- and this is the distinguishing feature -- it is data from the server about the position of the mobile element, so there is no picture being sent from the server how that is displayed. It is a combination of a picture and data that these distributed renderers need to then build up for their own sub-image, partial image, that is then displayed.’
[101]If Mr Viant was saying anything there that he had not already said in his reports or in cross-examination, about which I am not at all clear, I unable to draw anything from that answer which seems relevant to the issue of inventive step.[102]Going back to the integers of claim 11, in closing the argument that integer 5(A) (the microcontroller) was neither disclosed nor obvious was not pursued by Battlekart.[103]That leaves(a) the tracking system,(b) at least two electromagnetic emitters on the kart one of which must be an IR emitter and(c) a sensor with a camera capable of detecting IR radiation as the matters which, according to Battlekart, together constituted the key information disclosed in the Patent but which was not part of the CGK.[104]The defendants’ case was that the skilled team would have decided to use a tracking system like BlackTrax. Mr Densham’s evidence was that the skilled team, seeking to make a better karting experience and influenced by the prior art, would have seen the need for a tracking system and would have used BlackTrax or alternatively one of the other two tracking systems he referred to in his evidence.[105]Mr Viant’s point was that the skilled team would have known nothing about BlackTrax or similar tools but I have found that Mr Viant was not correct in that regard. Mr Viant was in no position to say whether the skilled team would have tried any of them, if so which, or how they would have assisted in the project. He had never heard of them before reading Mr Densham’s evidence because live experiences with moving items, i.e. the sort of entertainments and spectacles which require a tracking system, are not his field.[106]Mr Densham said that any or all of the tracking systems would have been tried. I have no reason to doubt Mr Densham’s evidence on this. I find that it would have been obvious to the skilled team to try any of the three tracking systems mentioned by Mr Densham with a reasonable expectation that it would significantly assist in creating a more engaging karting experience. For convenience I will assume that the skilled team would have gone forward using BlackTrax.[107]As Mr Densham explained, BlackTrax is a tracking system that uses IR transmitters on the object to be tracked. Optionally, any of one to three IR LEDs can be used. The emitted IR radiation is detected by a camera.[108]The one feature that the skilled team would have to adopt in order to perform the invention of claim 11 was to select the option of two or three IR LEDs for the kart when using BlackTrax.[109]Mr Viant said in his report that using one emitter would be the simplest approach and that it would not have been CGK to use two. In cross-examination he conceded that it would have part of the CGK that using one or two IR emitters were alternatives, each of which had pros and cons. He then said that whether it was obvious to use two depended on the ‘domain’ of use. Counsel pressed Mr Viant for some time, quite fairly, to explain what it was about the domain of the invention that would have made the use of two IR emitters not an obvious option within the CGK. I found Mr Viant’s answers both evasive and unpersuasive. If he was to make his point good, he needed to set out his reasoning properly. He did not.[110]Mr Densham pointed out that using either two or three IR emitters was an off-the-shelf option with BlackTrax and added that using two or three offered the twin advantages of redundancy and improved detection of orientation. He maintained this in cross-examination.[111]Mr Densham was the more convincing on this topic and I accept his evidence.[112]In my judgment a skilled team which had attended the Battlekart Disclosure would have thought it obvious at the priority date to use BlackTrax as a tool to create an improved karting experience something like the one presented by Battlekart. Choosing to have two or three IR LEDs on the karts would have been a readily available and obvious option. Claim 11 lacks inventive step over the Battlekart Disclosure.

The MIT Disclosure

[113]The information made available by the MIT Disclosure was that which would have been seen by the skilled team on a hypothetical visit to watch the students’ game in action. There was no confidential, contractual or other restriction placed on anyone who was passing by. The nature of that information was inferred from a report written by one of the students, Bradley Gross, and from what can be seen in a video made by Mr Gross.[114]Battlekart’s pleaded case was that the MIT Disclosure did not disclose(i) two infrared LEDs as emitters,(ii) the use of a microcontroller,(iii) the presence of a server as opposed to an FGPA used by the MIT students (and(iv) the presence of a kart, which amounted to the issue of whether the skilled team would have found it obvious to scale up the MIT game to a system as claimed.[115]In closing, Battlekart directed its argument to scaling up. The MIT game used small toy karts. Battlekart’s counsel described them as being the same size as ‘Matchbox’ toy cars – so not ‘karts’ as that term would have been understood to be used in claim 11.[116]Scaling up was not strictly the issue. A skilled team considering how to improve the experience of regular karting would have had in mind improvements to full-sized karting. The point was whether the team would have thought it practical to introduce the Mario Kart features of the MIT game into conventional karting.[117]Mr Viant identified several reasons why he thought that such a project would have been seen as impractical, listing difficulties that would have to be resolved and emphasising in particular that karting with human drivers involves safety concerns not in issue with toy karts. He was strongly of the view that the skilled team’s CGK would be insufficient to resolve these difficulties.[118]There are two problems with this evidence. First, Mr Viant was assuming that the skilled team would not have known about BlackTrax. Secondly, although he said that the CGK would have been insufficient he did not identify the gaps in the CGK of the skilled team which would have been filled in by the Patent, unless he was thinking of Figures 5 and 7, discussed above.[119]Mr Densham of course had BlackTrax very much in mind. His evidence was that the skilled team would have introduced the features of the MIT game using BlackTrax or a similar tool and that this would have led to a system as claimed in the Patent. He agreed that there would have been safety concerns and that some testing would have been done but he regarded this as routine. He thought that the skilled team would have been confident of success.[120]Mr Densham’s evidence did not give much detail about the steps required to introduce the Mario Kart features of the MIT game into conventional karting. But as between his and Mr Viant’s evidence, Mr Densham was the more reliable source regarding the views and expectations of a skilled team that had watched the MIT game in action and wanted to improve conventional karting. In addition, his evidence was consistent with Mr Millecam’s evidence that the Chaos Kart project started with a prototype of a size something like the MIT game and that it had been scaled up using BlackTrax.[121]I find that claim 11 lacks inventive step over the MIT Disclosure.

The Disney Application

[122]Leaving aside the microcontroller and the multiple projection system which are not relevant, the differences between the Disney Application and claim 11 were(i) no tracking system,(ii) no two IR radiation emitters on the karts and(iii) no sensor in the form of a camera capable of detecting IR radiation.[123]For the reasons I have given in relation to the Battlekart Disclosure, I find that claim 11 lacks inventive step over the Disney Application.[124]The short point which applies to all three items of prior art is that Mr Densham’s technical background made him, of the two experts in the proceedings, the more reliable source of evidence on the CGK. It led to my finding that BlackTrax and equivalent tracking systems were part of the CGK. Mr Densham, the only expert who knew anything at all about BlackTrax before this trial and who even now knows much more than Mr Viant, broadly said that BlackTrax would have taken care of the transition from each of the three cited items of prior art to a claim 11 system. I was given no good reason to disbelieve Mr Densham on this.

No Contribution to the Art

[125]The defendants’ argument that claim 11 neither discloses nor renders plausible any contribution to the art adds nothing to their argument on inventive step.

Added Matter

[126]No point was raised regarding the law on added matter. Arnold LJ has recently explained the reasoning behind it and why the rule is strictly applied, see Generics (UK) Ltd v AstraZeneca AB [2025] EWCA Civ 903, at [11] to [13].[127]This is the relevant disclosure in the application for the Patent as filed:
‘The emitter 210 preferably comprises at least one electromagnetic radiation source, which can be an infrared lamp. The emitter 210 more preferably comprises at least two electromagnetic radiation sources. Having two sources enables one of the sources to always 20 be active in the event of the other one failing. The emitter 210 even more preferably comprises a first infrared lamp 211 and a second infrared lamp 212. The electromagnetic radiation source is preferably of variable intensity. Preferably, the on-board computer 230 sends power to the electronic interface 240, which must emit the infrared LED 211, 212. In one embodiment of the invention, the infrared LED 211, 212 can have two states: switched-off and switched-on at full power.’
[128]The parties were agreed that this passage discloses an emitter with alternatively(a) one electromagnetic radiation source which is IR, or(b) two electromagnetic radiation sources, or(c) two electromagnetic radiation sources which are both IR. It does not disclose an emitter comprising at least two electromagnetic sources of which only one is IR.[129]The issue was whether integer G of claim 1 on a proper construction does disclose an emitter comprising at least two electromagnetic sources of which only one is IR.[130]This is integer G of claim 1:
‘and in that each mobile element further comprises an emitter comprising at least two electromagnetic radiation sources comprising an infrared emitter, the emitter being arranged to transmit a signal enabling the mobile element to be located by the locating system.’
[131]Mr Viant gave some evidence on this but did not say that there were terms of art which required explaining. This is a matter of interpretation for the court.[132]Battlekart submitted that the body of the specification nowhere teaches the use of an emitter comprising at least two electromagnetic sources of which only one is IR. I will assume it does not but a claim can be a source of disclosure in a Patent just as much as the body of the specification, a principle of law which was not challenged by Battlekart. If a claim, properly understood, discloses matter, it makes no difference whether or not it is disclosed elsewhere.[133]Battlekart’s main argument was that in integer G the words ‘sources comprising’ would be understood to mean ‘each source comprising’. So the emitter comprises at least two electromagnetic radiation sources each of which comprises an IR emitter. Both must be IR.[134]I disagree. In my view the words ‘sources comprising’ mean what they say. The words qualify ‘at least two electromagnetic radiation sources’. The at least two electromagnetic radiation sources must collectively comprise at least one IR emitter. There may be more than one IR emitter but there need not be. The reader is therefore told that there may be at least two electromagnetic radiation sources of which only one is IR.[135]The Patent is invalid for added matter. Conclusion[136]The Patent is invalid for lack of inventive step and for added matter.