[2024] UKUT 71 (AAC)

PLP further (and relatedly) argues that the FTT erred in law because it did not properly take into account the evidence PLP put before it, in particular that of the two professors.

The professors’ evidence was not with regard to the factual context, as summarised at paragraph 35a above. Nor was it opinion evidence directly on the issue before the FTT – the likely effect of disclosure of criteria used in the automated triage process, on immigration controls, on crime prevention/detection, or, more specifically, on the government’s sham marriage referral and investigation scheme. It was not surprising that the professors did not give opinion evidence on such matters, as (i) they did not know what the non-disclosed criteria were; and (ii) in any case, their area of expertise was not the phenomenon “sham marriages” and those organising and taking part in them (such that they might have an informed view on how those involved with sham marriages might react to disclosure of criteria used by the government to detect such marriages).

Rather, the professors’ evidence, so far as relevant to this ground of appeal, was at the more ‘generic’ level of how disclosure of criteria used in “automated” systems generally might, or might not, affect the efficacy of those automated systems in achieving their ends. The professors’ opinion evidence did not draw any specific, firm conclusions on the matters before the FTT (once again, not surprising, given their backgrounds and circumstances, as just described). But they did caution against a “broadbrush” approach to assessing the effect of disclosure on the efficacy of such automated systems. Their arguments focused on the phenomenon they called “gaming the system” – i.e. (per Professor Tomlinson, quoted verbatim at [46]) altering behaviour so as to seek to present a lawful marriage, or to do so in a way that could not be mitigated or guarded against – and expressed their opinion that

Professor Tomlinson’s witness statement advocated (as can be seen from the extract set out verbatim at [46]) “close analysis of the level of risk associated with disclosing a particular part of an automated system”; “detailed appraisal of whether any particular criteria are capable of being gamed” and, if so, “a realistic assessment of the actual likelihood of gaming occurring”. In effect, it was a “stepped” approach to deciding the effect of disclosing criteria, focusing on “gaming the system” as the principal risk.

I do not accept that it was perverse or irrational for the FTT, having considered the professors’ evidence, and indeed PLP’s parallel submissions at the hearing, to have come to the conclusion it did on the likely effect of disclosure on immigration controls and prevention/detection of crime – but without following the approach to decision-making advocated by Professor Tomlinson and summarised immediately above:

An additional argument in Mr Paines’ skeleton argument was that, because the professors’ evidence was not tested in cross examination, or questioned by the FTT, it should have been “accepted” by the FTT. It cited Griffiths v TUI (UK) Ltd [2023] 3 WLR 1204, in which the Supreme Court upheld the general rule in civil cases that a party is required to challenge by cross-examination the evidence of any witness of the opposing party on a material point which they wish to submit to the court should not be accepted; that extended to witnesses as to fact and expert witnesses; the purpose of the rule, in an adversarial system of justice, was to make sure the trial was fair; the rule should not be applied rigidly.

Here, the professors’ evidence was not as to the factual context, or as to their opinion on the question before the tribunal (the likely effect of disclosure, etc); rather, it was as to the approach to be taken in deciding the question before the tribunal (“stepped” versus more “broadbrush”); in my view, there was no unfairness to PLP or the professors in not being cross examined by IC on this point, as it was self-evident from the parties’ cases that IC took a different view as to the proper approach to making this decision (indeed, it was IC’s answer to the question, in the IC decision notice, that was the subject matter of the appeal). Neither fairness or justice would require, in the circumstances of this case, that the FTT “accept” PLP’s witnesses’ opinions as to the method for making the evaluative judgement that it was for the FTT to make, on grounds that the witnesses’ opinions on that point had not been subject to cross examination: both sides knew the other’s positions, and could, and did, argue against them; the final evaluative judgement fell, quite correctly, to be made by the FTT itself. To impose the general rule in Griffiths in this case would, in my view, be the sort of over-rigid application against which the case itself warns.