Held, appeal dismissed. (1) An appeal under section 2B of the Special Immigration Appeals Commission Act 1997 was not an appeal from a court. It was an appeal from an administrative decision-maker who had particular expertise and institutional competence in questions of national security. Subject to the constraints exerted by the authorities, that right of appeal gave SIAC power to decide questions of fact and of law. It was clear that an appeal and an application for judicial review were fundamentally different, in that an appellant could challenge the merits of a decision, whereas a claimant in an application for judicial review could not do so. For those reasons, SIAC did not err in law in refusing to treat the appeal as an application for judicial review (para 170, 196, 197, 198) .

(2) On an appeal, the appellate body could take into account evidence which post-dated the impugned decision, as long as that evidence was capable of casting light on events before and at the time of the decision. None of the authorities prevented SIAC, on a section 2B appeal, from making findings of fact on the balance of probabilities. As long as it respected the limits established by the authorities when it considered a challenge to the Secretary of State’s assessment of national security, SIAC could also make whatever findings of fact it considered it was able to make on the evidence, on the balance of probabilities, and which, in its expert judgment, it considered that it was appropriate to make. The contentious aspects of the assessment, in a case like the present, would often turn on questions of motivation, which would depend on inferences, or on similar issues. SIAC was not a jury deciding whether or not a defendant intended to commit the crime charged on an indictment. Nevertheless, in an appropriate case, SIAC might have judged that the evidence enabled it to make a finding about a person’s motivation. Since a finding about motivation necessarily involved an assessment based on inferences from primary facts, SIAC should bear in mind that its finding about motivation could not displace a contrary assessment by the Secretary of State, as long as there was material which would rationally support such a contrary assessment. A judgment SIAC made about whether to make a finding, or not, was unlikely to be susceptible to challenge on an appeal on a point of law (paras 171, 173, 174, 175, 178, 196, 197, 198).

(3) In every respect in which it was asked to substitute its own assessment for the relevant assessment of the Secretary of State, SIAC refused to do so, but, instead, reviewed the Secretary of State’s assessment to see whether it had a rational basis. It was right to do so (para 195, 196, 197, 198).