IN THE MATTER OF APPLICATION NO. 9204959.2 BY FUJITSU LIMITED [1997] EWCA Civ 1174

EWCA-Civ

IN THE MATTER OF APPLICATION NO. 9204959.2 BY FUJITSU LIMITED

[1997] EWCA Civ 1174 · 1997-03-06

This appeal raises, not I expect for the last time in this Court, the question of whether a patent application falls within the ambit of Section 1(2) of the Patents Act l97l and is therefore excluded from being a patentable invention.

On 6 March l992, the appellants, Fujitsu Ltd applied in this country for a patent claiming priority from a Japanese application. The application was published under No. 2254458A, but was objected to by the Examiner upon the ground that it related to a method for performing a mental act and to a programme for a computer and therefore was excluded by Section 1(2)C of the Act. That view was upheld, after an oral hearing, by Mr Haselden, a Principal Examiner acting for the Comptroller. The appellants appealed. Their appeal was rejected by Laddie J. Against his judgment and Order the appellants appeal.

The statutory provisions

Section l of the Patents Act l977 defines what are patentable inventions and also lists some things that are not patentable. The relevant parts of that section read:

(1) A patent may be granted only for an invention in respect of which the following conditions are satisfied, that is to say -

(a) the invention is new;

(b) it involves an inventive step;

(d) the grant of a patent for it is not excluded by subsections (2) and (3) below;

and references in this Act to a patentable invention shall be construed accordingly.

(2) It is hereby declared that the following (among other things) are not inventions for the purposes of this Act, that is to say, anything which consists of -

(a) a discovery, scientific theory or mathematical method;

(b) a literary, dramatic, musical or artistic work or any other aesthetic creation whatsoever;

(c) a scheme, rule or method for performing a mental act, playing a game or doing business, or a programme for a computer;

(d) the presentation of information;

but the foregoing provisions shall prevent anything from being treated as an invention for the purposes of this Act only to the extent that the patent or application for patent relates to that thing as such.

....

Those provisions have to be construed in the light of the European Convention and with the help of the judgments given by the European Patent Office. As Nicholls LJ said in Gales Application

(1991) RPC 305

at 322.

"One of the purposes of the l977 Act was to give effect to the European Patent Convention. Thus, section 77(1) provides that a European patent (UK), by which is meant a European patent designating the United Kingdom, shall as from a prescribed date be treated for the purposes of parts 1 and 3 of the Act as if it were a patent under the Act granted in pursuance of an application made under the Act. Section 77(4) provides that where a European patent (UK) is revoked in accordance with the European Patent Convention, the patent shall be treated for the purposes of parts 1 and 3 of the Act as having been revoked under the Act.

The Act had a further purpose. The Act did not merely enact the statutory provisions necessary for the provisions of the Convention regarding European patents to take effect in this country. The Act also had a harmonisation objective. On the signature of the Convention for the European Patent for the Common Market, referred to in the Act as the Community Patent Convention, and not to be confused with the European Patent Convention, the governments of the member states of the European Community resolved to adjust their laws relating to patents so as to bring those laws into conformity with the corresponding provisions in the European Patent Convention and other conventions. Accordingly, when construing and applying section l(l) and (2) of the Act, the court must have regard to the legislative intention with which those subsections were framed, namely, that they were framed so as to have, as nearly as practicable, the same effect in the United Kingdom as the corresponding provisions in Article 52(1), (2) and (3) of the European Patent Convention have in the territories in which that Convention applies. That is the effect of section 130(7) in the present case.

From this brief reference to the European Patent Convention one point which emerges is that it is of the utmost importance that the interpretation given to section l of the Act by the courts in the United Kingdom, and the interpretation given to Article 52 of the European Patent Convention by the European Patent office, should be the same. The intention of Parliament was that there should be uniformity in this regard. What is more, any substantial divergence would be disastrous. It would be absurd if, on an issue of patentability, a patent application should suffer a different fate according to whether it was made in the United Kingdom under the Act or was made in Munich for a European patent (UK) under the Convention. Likewise in respect of opposition proceedings."

The patent application

The application is entitled "Method and Apparatus for Creating Synthetic Crystal Structure Images." At the heart of the invention is a method for modelling a crystal structure for use in designing inorganic materials in the fields of chemistry and physics. The basic idea utilises a computer programmed so that the operator can select an atom, a lattice vector and a crystal face in each of two crystal structures displayed on the display unit. Upon instruction the computer, using the selected requirements, converts data representing the physical layouts of the two crystal structures into data representing the physical layout of the crystal structure that would be obtained by combining the original two structures in such a way that the two selected structures are superposed. The resulting data is then displayed to give a picture of the combined structure.

I understand that the crystal structures which the inventor particularly had in mind are those of semiconductors and superconductors. Thus a scientist wishing to investigate what would result if he made a new material consisting of a combination of two existing compounds would enter data representing each of those compounds into the computer. The structure of the two compounds would then be displayed. The operator then selects how they should be joined by selecting the relevant atom, the lattice vector (atomic bond) and a plane. The computer then generates and displays the new structure using the data supplied.

The specification opens with a general statement as to what the invention relates. It then explains how in the manufacture of new inorganic materials, such as superconductors materials and semiconductors, it is known to produce models to study in advance their physical attributes. The specification states:

"Conventionally, the modelling of a crystal structure of an inorganic material is carried out by operations of assembling a plastic model of structure elements and tracing the assembled structure. In this conventional modelling of the crystal structure, as an operator actually assembles the plastic models of the structure elements by hand, the assembly is hard for the operator."

The specification then sets out the consistory clauses which show that the invention is claimed both as a method and as a computer apparatus. The relevant claims are:

"1. A method of processing first and second images representing first and second crystal structures to produce a third image representing the structure of a synthetic crystal structure, the first and second images being stored as respective first and second sets of data items, the first set of data items representing, in a first coordinate system, the plurality of atoms and lattices in the first crystal structure, and the second set of data items representing, in a second coordinate system, the plurality of atoms and lattices in the second crystal structure, which method comprises the steps of:

using the computing means for selecting a pair of crystal faces, one from each of the first and second crystal structures, having respective mutually-similar arrangements of atoms, and, for each crystal face of the selected pair, selecting an atom and a linear array of atoms in the face;

using the computing means to transform the second set of data items to produce a third set of date items representing, in the said first coordinate system, the respective atoms of the second crystal structure arranged so that the selected atom of the second crystal structure can be superposed on the selected atom of the first crystal structure and so that atoms of the selected linear array of the second crystal structure can be superposed respectively on those of the selected linear array of the first crystal structure, and so that the selected crystal faces then coincide in a common plane, the remaining atoms of the second crystal structure being located to one side of that plane whilst the remaining atoms of the first crystal structure are located to the opposite side of that plane;

using the computing means to combine the first and third sets of data items together to produce the third image as a representation of a crystalline combination of the said

first and second crystal structures; and

using display means of the computing means to display the resulting third image in a form by which the physical properties of the crystalline combination can be studied.

9. A method of manufacturing a structure which is a crystalline combination of two crystal structures, the method comprising an investigation of the effects of combining the two crystal structures using a method according to any one of the preceding claims.

10. A computer apparatus for creating a computer image of a synthetic crystal structure formed of a first crystal structure having a plurality of atoms and lattices and a second crystal structure having a plurality of atoms and lattices, said apparatus comprising:

computer storage means for ....

selection means for selecting from ....

specifying means, coupled to said selecting means, for specifying ....

transformation means for transforming said ....

computer display means for displaying ...."

The Principal Examiner held that the invention amounted to no more than a programme for a computer and also was no more than a method of performing a mental act. It was therefore excluded by Section l(2)(c) of the Act.

The Judge concluded that the claims in form were not to a computer program as such, but that:

"In this case, Fujitsu's application leaves it to the operator to select what data to work on, how to work on it, how to assess the results and which, if any, results to use. The process is abstract and the result of use of it is undefined. What is produced is not an inevitable result of taking a number of defined steps but is determined by the personal skill and assessment of the operator. As such it consists in substance of a scheme or method for performing a mental act and is unpatentable."

The law

Section 1(2)(c) of the Act has been considered by this Court in Merrill Lynch's Application

(1989) RPC 561

and in Gales' Application . In both those cases the Court drew attention to the proviso to Section 1(2) which states that the "things", referred to in the subsection, should only be excluded "to the extent that a patent or an application for a patent relates to that thing as such."

In Merrill Lynch the applicants submitted that the question for the Court was to decide whether the subject matter of the claim was a computer program. If it was, it was not patentable. If it was not, then the invention was not excluded from patentability by Section l(2). Thus it was said that a piece of machinery (a computer) which follows the instructions of a computer program was patentable, although the program itself would be excluded from patentability by the Section. That was rejected by the Court of Appeal. Fox LJ said at page 569:

"It seems to me to be clear, .... that it cannot be permissible to patent an item excluded by section l(2) under the guise of an article which contains that item - that is to say, in the case of a computer program, the patenting of a conventional computer containing that program. Something further is necessary. The nature of that addition is, I think, to be found in the Vicom case where it is stated:

'Decisive is what technical contribution the invention makes to the known art.'

There must, I think, be some technical advance on the prior art in the form of a new result (eg a substantial increase in processing speed as in Vicom )."

By that statement Fox LJ was making it clear that it was not sufficient to look at the words of the claimed monopoly. The decision as to what was patentable depended upon substance not form. He also went on to point out the importance of considering whether the invention made a technical contribution, despite the fact that neither the statute nor

Article 52 of the Convention

lays down that the matter, which would result in the invention not relating to the thing as such, must provide a technical contribution. It would therefore seem that as a matter of words, if for instance the patent was not confined to a computer program, then it could not be excluded under subsection (2), as to an extent the patent would not relate to the computer program as such. However it is and always has been a principle of patent law that mere discoveries or ideas are not patentable, but those discoveries and ideas which have a technical aspect or make a technical contribution are. Thus the concept that what is needed to make an excluded thing patentable is a technical contribution is not surprising. That was the basis for the decision of the Board in Vicom . It has been accepted by this Court and by the EPO and has been applied since l987. It is a concept at the heart of patent law.

The reasons for the decision of the Technical Board in Vicom T208/84, 1987 2 EPOR 74 have to be read against the background of the invention claimed. It was for a method of digitally processing images and an apparatus for carrying out the method. The invention as claimed involved scanning the elements of a data array to produce a convolved array and then repeating the scanning so that the last convolved data array generated had the enhanced qualities required. That claim was objected to as being a method of performing a mental act as such and as a computer program as such contrary to Articles 52(2) and (3) of the Convention.

The Board allowed the appeal. They drew a distinction between a method of performing a mental act which was not patentable and a technical process. They pointed out that use of a mathematical process did not produce a technical result. They went on:

"In contrast thereto, if a mathematical method is used in a technical process, that process is carried out on a physical entity (which may be a material object but equally an image stored as an electric signal) by some technical means implementing the method and provides as its result a certain change in that entity. The technical means might include a computer comprising suitable hardware or an appropriate programmed general purpose computer.

The Board, therefore, is of the opinion that even if the idea underlying an invention may be considered to reside in a mathematical method a claim directed to a technical process in which the method is used does not seek protection for the mathematical method as such ."

The Board then came to consider the objection that the invention was excluded as it related to a computer program as such. They rejected that objection, essentially upon the same reasoning. They said:

"Generally claims which can be considered as being directed to a computer set up to operate in accordance with a specified program (whether by means of hardware or software) for controlling or carrying out a technical process cannot be regarded as relating to a computer program as such and thus are not objectionable under Article 52(2)(c) and (3) EPC.

....

Generally speaking, an invention which would be patentable in accordance with conventional patentability criteria should not be excluded from protection by the mere fact that for its implementation modern technical means in the form of a computer program are used. Decisive is what technical contribution the invention as defined in the claim when considered as a whole makes to the known art."

Mr Birss submitted that the decision in Vicom showed that patent applications for processing images of real things were not excluded from being patentable. He took us to the claim which had been considered by the Examining Division which limited the invention to a method of filtering a two-dimensional data array and compared that with the claim that was allowed which claimed a method of processing images. He submitted that it was the change from filtering to processing real images that supplied the technical contribution.

The reasoning in Vicom as to what was the technical contribution is not easy to ascertain. However I do not read the Decision as concluding that all claims to processing real images are patentable and I can see no reason why, if they are, the same reasoning should not apply to all useful images. As I read the Decision, the Board saw a technical contribution, namely the generation of the enhanced picture. As the principal Examiner pointed out:

"The numbers which are mathematically processed in Vicom do not merely determine the intellectual content of the images which are displayed, but are also the technical means which cause the display to operate to a technical level. Thus in Vicom manipulating numbers in the manner described affects the technical quality of the image. So in Vicom , the invention concerned the technical representation, or technical control of what is displayed and not the information content of what is displayed."

In my view Vicom does not support the submission that claims to processing of real images are allowable. The technical contribution was not the fact that an image was being produced. It was the way the enhanced image was produced.

In Gale this Court had to consider a patent application for a ROM programmed to carry out a method of calculating a square root of a number. Nicholls LJ who gave the leading judgment described the working of a computer and said:

"In principle, the instructions in a computer program do no more than prescribe a particular manner of operation for which it was constructed. Thus writing a fresh set of instructions for use in a computer in particular circumstances or for particular purposes cannot in itself be regarded as inventive."

He went on to point out that, to be used in a computer, a series of instructions had to be recorded in some physical form perhaps on a disc in a ROM. He said that if the instructions qua instructions were not patentable, they were not patentable merely because they were recorded on or in a known piece of apparatus. The disc on ROM was "merely the vehicle used for carrying" the instruction.

"... the physical differences are not material for patent purposes, because they constitute no more than the use of a compact disc for its intended purpose. Likewise with a disc or ROM which records or reproduces a new set of instructions, if those instructions are recorded on a conventional disc, or are stored in a ROM using conventional methods. To decide otherwise would be to exalt form over substance."

He went on to conclude that the application before him did not contain a technical contribution and therefore was a computer program which was excluded from patentability.

I, like Nicholls LJ, have difficulty in identifying clearly the boundary line between what is and what is not a technical contribution. In Vicom it seems that the Board concluded that the enhancement of the images produced amounted to a technical contribution. No such contribution existed in Gale's Application which related to a ROM programmed to enable a computer to carry out a mathematical calculation or in Merrill Lynch which had claims to a data processing system for making a trading market in securities. Each case has to be decided upon its own facts.

Does the application consist of a program for a computer as such?

The Principal Examiner considered in depth the submissions put forward on behalf of the Appellants on this topic and concluded that the invention did consist of a computer program as such. He held that it did not provide any technical contribution of the type required. He said:

"In essence, this brings me back to the question I posed above which is whether the fact that what is displayed is a technical artefact, viz a crystal structure, is sufficient to confer technical character on the full invention on the facts in this case. In this respect however, the opening page of the specification points out that it is known to model inorganic chemicals used in plastic models of structural elements assembled by hand by an operator and it is I think against that background that the substance of the present invention is seen in its proper context. In the absence of any disclosure to the contrary, the display must be taken to be wholly conventional at the technical level so the present invention amounts to no more than the provision of a technically conventional computer programmed to combine the contents of two displays of crystal structures in a particular way to produce a third composite crystal structure. In fact of course, all that the display is arranged to do is to substitute elements of one structure in another, thus mimicking what has previously been done manually with plastic models. Thus, what is disclosed is in substance a conventional computer system programmed to display pictures of crystal structures. While crystal structures undoubtedly do lie in a technical field ... the pictures displayed are simply substitutions derived by taking part of one picture and superposing it on another picture and it seems to me that this process is not of a technical nature but is no more than a purely intellectual process of substitution. ... I do not dispute that a designer could use the pictures displayed in the process of designing a new compound ..., but it still seems to me that the substance of the invention disclosed is simply a conventional computer programmed to display the same images as were previously produced using plastic models and in my view this does not involve a technical advance of the kind which I am required to find."

The Judge held:

"I have already referred to the essence of Fujitsu's development. It is clear that, in form at least, claims are not to programs as such. It follows that, prima facie, they avoid the 'program' exclusion under Section 1(2). However as Fox LJ said in Merrill Lynch something further is needed. The real issue it seems to me, is whether the application also avoids the other exclusions under Section l(2). If it does not, the application will fail. Whether, in those circumstances, the grounds of failure are stated to be that the invention is only for a program or that it is, for example, a method for performing a mental act is a matter of semantics."

He went on to hold that the application was excluded as it consisted in substance of a scheme or method for performing a mental act.

I am not sure whether the Judge came to any conclusion as to whether the application consisted of a computer program as such. Clearly he considered that in form the claims were not excluded from being patented, but seemed to believe that there was no difference in this case between the two grounds of exclusion.

Mr Birss sought to rely upon the form of the claims. He submitted that claim l0, directed as it was to a computer apparatus having a number of features and claim 9 directed to a method of manufacturing a structure could not be said to relate to an invention consisting of a computer program as such.

That submission cannot be right having regard to the judgment of Nicholls LJ in Gale. In that case, I held at first instance that the ROM claimed was not excluded as it was an article which had been altered during manufacture so as to perform the function of the method or program defined by the claim. The Court of Appeal decided that that was not correct and that the Court should look at the claims as a matter of substance. It was both convenient and right to strip away, as a confusing irrelevance, the fact that the claim was for "hardware".

There is only one invention. The fact that it is claimed as a method, a way of manufacture or an apparatus having appropriate features is irrelevant. Further there is no dispute as to what the invention is. In summary it uses a computer program so that an operator can select an atom, a lattice vector and a crystal face in each of two crystal structures displayed. The computer, upon instruction and using the program, then converts data representing the physical layouts of the two crystal structures into data representing the physical layout of the structure that is obtained by combining the original two structures in such a way that the selected atoms, the selected lattice vectors and the selected faces are superposed. The resulting data are then displayed to give a picture of the resulting combined structure. Clearly the whole operation revolves around the computer program and the question for decision is whether there is a technical contribution so that it cannot be said that the invention consists of a computer program as such.

Mr Birss put forward two grounds for concluding that the application included a technical contribution. First, relying on Vicom, he submitted that the technical contribution was provided by the processing of real images or structures. I have already concluded that Vicom does not support so rigid a view. Thus this submission must be rejected. Second, he submitted, that the application provided a new tool for modelling crystal structure combinations which relieved the chemist of the laborious task of building a model. It provided a solution to the problem of providing a quick and error free way of creating real images of two crystal structures joined together.

Mr Birss is right that a computer set up according to the teaching in the patent application provides a new "tool" for modelling crystal structure combinations which avoids labour and error. But those are just the sort of advantages that are obtained by the use of a computer program. Thus the fact that the patent application provides a new tool does not solve the question of whether the application consists of a program for a computer as such or whether it is a program for a computer with a technical contribution.

I believe that the application is for a computer program as such. I agree in general with the reasons of the Principal Examiner which I have quoted. In Vicom the technical contribution was provided by the generation of the enhanced display. In the present case the combined structure is the result of the directions given by the operator and use of the program. The computer is conventional as is the display unit. The two displays of crystal structures are produced by the operator. The operator then provides the appropriate way of superposition and the program does the rest. The resulting display is the combined structure shown pictorially in a form that would in the past have been produced as a model. The only

advance is the computer program which enables the combined structure to be portrayed quicker.

I conclude that the application does not relate to a patentable invention as it is excluded by Section 1(2)(C) as being a program for a computer as such.

Does the claim consist of a method of performing a mental act as such?

The fact that a patent application consists of a program for a computer does not mean that it does not also consist of a method of performing a mental act. The contrary is not true. In this case the computer program is the result of intellectual input, but whether the claimed invention, which incorporates operator control, consists of a method of performing a mental act as such is doubtful. As there is no need to decide this issue, I conclude that an in-depth analysis is best left to be dealt with on another occasion. However, in the light of the submissions of Counsel I will set out my views on the point of construction that was argued.

Mr Birss submitted that the words "a method for performing a mental act" in Section 1(2)(c) should be construed as only covering methods which the human mind carries out. They should not be construed to include the sort of acts which a human mind could do. If so, the Fujitsu application was not excluded as it related to a specific way of modelling crystal structures not carried out by the human mind.

Mr Silverleaf QC who appeared for the Comptroller submitted that the narrow construction sought to be placed upon the words "for performing a mental act" was wrong, contrary to authority and involved reading into the Act words such as : "as done by the mind".

In support of the narrow construction Mr Birss referred to the Board's decision in Vicom. He suggested that the invention in that case could have been performed by the human mind, but was held to be patentable because the human mind did not actually work in the way claimed. The distinction drawn by Mr Birss may be correct in fact, but the reasoning is not. The reason why the Board concluded that the invention was patentable was because they concluded there was a technical contribution. The Board did not analyse how the human mind works and therefore that did not play a part in their considerations.

Mr Birss also relied on Pettersson T1002/92 (1996) EPOR 1. The invention in that case related to a system for handling customers queuing for a number of service points. The Technical Board held at page 8:

"The wording of Claim l leaves no doubt that protection is sought for a 'system which is capable to determine the queue sequence of customers', and thus for a three-dimensional object with the aforementioned capacities. Claim l explicitly indicates that this system comprises:

'a turn-number allocation unit, a selection unit, terminals, an information unit and computing means.'

Hence, the wording employed in the claim defines a technical item with at least five construction components, which item clearly belongs to the category of an apparatus."

The Board concluded that in such a case there was a mix of technical and non-technical elements which meant that the claim was not excluded from patentability. Again there was no analysis of how the human mind works. The invention was held to be patentable because there was a technical contribution with the result that it did not relate to a method of performing a mental act as such.

There are good reasons to reject the narrow construction. First, a decision as to whether an invention is patentable as consisting of a method of performing a mental act as such should be capable of determination without recourse to evidence as to how the human mind actually works. If it were to the contrary, the section would pose an extremely difficult problem. Second, the narrow interpretation appears to introduce a consideration of novelty which is covered in Section 1(1)(a). Third, the words used as "a mental act" suggest any mental act whether done before or not.

A similar but not identical submission was made in Wang Laboratories Inc's Application

(1991) RPC 463

as appears from this extract of my judgment:

"Before turning to the claims, I must deal with a submission of Mr Burkill, who appeared for the applicant. He submitted that the words "a scheme, rule or method for performing a mental act" in section 1(2)(c) only excluded schemes, rules or methods which were intended to be performed and were capable of being performed in the human mind. He submitted that the word "for" introduced a subjective element. Thus, as claim l had as its basis steps which were not intended to be carried out by a human, in that the human mind would not go through those steps, the basis of the claim was not excluded matter.

The word "for" does not, in my view, introduce a subjective element. It means "for the purposes of". The fact that the scheme, rule or method is part of a computer program and is therefore converted into steps which are suitable for use by a person operating the computer does not matter. What is excluded from being patented is a scheme, rule or method for performing a mental act, whatever mental steps or process is involved. As I pointed out in Gale's Application , it is a question of fact to be decided in each case whether the claimed invention is more than a claim to an invention for a disqualified matter. Just as a claim to a disc containing a program can be in fact a claim to an invention for a computer program, so can a claim to steps leading to an answer be a claim to an invention for a performing a mental act. The method remains a method for performing a mental act, whether a computer is used or not. Thus a method of solving a problem, such as advising a person whether he has acted tortiously, can be set out on paper, or incorporated into a computer program. The purpose is the same, to enable advice to be given, which appears to me to be a mental act. Further, the result will be the advice which comes from performance of a mental act. The method may well be different when a computer is used, but to my mind it still remains a method for performing a mental act, whether or not the computer program adopts steps that would not ordinarily be used by the human mind."

Mr Birss submitted that the reasoning in my judgment in Wang was flawed. He submitted that it was not possible to perform a mental act using a computer and a claim to a method of using a computer could not be a claim to a method of performing a mental act. As a matter of semantics that may be right, but as has been made clear in Merrill Lynch and Gale , it is necessary to look at the substance of the application when dealing with the question of whether it is patentable. A claim to a computer operating in a particular way is no more patentable than a claim to a computer program. A claim to a method of carrying out a calculation (a method of performing a mental act) is no more patentable when claimed as being done by a computer than when done on a piece of paper. Methods of performing mental acts, which means methods of the type performed mentally, are unpatentable, unless some concept of technical contribution is present.

The task of arriving at the conclusion I have reached, namely that this appeal should be dismissed, has been made easier by the clear and pertinent submissions of Counsel.

ROCH LJ

I agree. The creation of diagrammatic images of physical objects on the visual display units of computers which can be turned, revolved and altered at the bidding of the computer operator is not new. In my opinion, what the appellants have done here is no more than to produce, brilliant though it may be, a new computer programme. The invention may be new but as it is no more than a computer programme it is not patentable.

LEGGATT LJ

I too agree that for the reasons given by Aldous LJ this appeal should be dismissed.

ORDER

Appeal dismissed with costs; order for a section 20 extension, as handed in; leave to appeal to the House of Lords refused.

Cited in 16 later judgments

and 7 more of the most senior