“In our judgment an application to strike out in the FTT under r 8(3)(c) should be considered in a similar way to an application underCPR 3.4 in civil proceedings (whilst recognising that there is no equivalent jurisdiction in the FTT Rules to summary judgment under Pt 24). The tribunal must consider whether there is a realistic, as opposed to a fanciful (in the sense of it being entirely without substance), prospect of succeeding on the issue at a full hearing, see Swain v Hillman[2001] 1 All ER 91 and Three Rivers[2000] 3 All ER 1 at [95],[2003] 2 AC 1 per Lord Hope of Craighead. A 'realistic' prospect of success is one that carries some degree of conviction and not one that is merely arguable, see ED & F Man Liquid Products Ltd v Patel[2003] EWCA Civ 472 , [2003] 24 LS Gaz R 37. The tribunal must avoid conducting a 'mini-trial'. As Lord Hope observed in Three Rivers , the strike-out procedure is to deal with cases that are not fit for a full hearing at all.”
“29 … the doctrine of abuse of process is not part of the doctrine of res judicata, and it is still applicable to tax cases. In Littlewoods, Henderson J held that HMRC were unable to advance the position that the tax was not due in defending the claim for interest because to do so would be an abuse of process, irrespective of the non-application of issue estoppel to tax cases: [250]. So the fact that issue estoppel does not apply to tax cases appears to be no bar to a court concluding that re-opening a decided issue is an abuse of process. 30. HMRC relied on Hunter v Chief Constable of the West Midlands Police[1982] AC 529 for a statement of what abuse of process was: “… [abuse of process] concerns the inherent power which any court of justice must possess to prevent misuse of its procedure in a way, which although not inconsistent with the literal application of its procedural rules, would nevertheless be manifestly unfair to a party to litigation before it, or would otherwise bring the administration of justice into disrepute among right-thinking people” page 536 C per Lord Diplock. 31. The statement in Hunter is very general and there might be room for doubt whether it extends to the circumstances in this case. However, the authorities of Littlewoods at §250 and SCF Finance Co Ltd v Masri[1987] 1 QB 1028 are more specific. Abuse of process appears to be very like issue estoppel save perhaps for flexibility where there are special circumstances: “a litigant who has had an opportunity of proving a fact in support of his claim or defence and has chosen not to rely on it is not permitted afterwards to put it before another tribunal…. … it would be an abuse of process of the court to raise in subsequent proceedings matters which could and should have been litigated in earlier proceedings…” page 1049 C-F, per Ralph Gibson LJ delivering the unanimous judgment of the Court of Appeal, also citing Lord Kilbrandon in the Privy Council that abuse of process “‘is limited to cases where reasonable diligence would have caused a matter to be earlier raised; moreover, although negligence, inadvertence or even accident will not suffice to excuse, nevertheless ‘special circumstances’ are reserved in case justice should be found to require the non-application of the rule.’ “ And unlike issue estoppel, abuse of process applies to tax cases. So I find that abuse of process does prevent previously litigated issues being re-tried between the same parties in tax cases unless there are special circumstances.”