Proving foreign law where there has been an earlier court decision

Questions of foreign law are treated, in English proceedings, as questions of fact. However, where a question of foreign law has already been decided in another case by (broadly) the English courts, that can be admissible in other proceedings (see section 4(2) of the Civil Evidence Act 1972), provided that that evidence is relevant. The issue in this case was whether it matters if the relevant part of the earlier decision was made obiter. Warren J held that it did not matter: "Although such a judgment cannot be cited as a binding precedent, obiter conclusions and reasoning can frequently be of enormous assistance to another judge grappling with the same issues. And so, although not a binding authority, such a judgment can properly be described as a persuasive (if it is) authority. Whether it is in fact persuasive will depend on the cogency of the reasoning; a conclusion with no reasoning may carry very little evidential weight if the conclusion is challenged. The judgment of Andrew Smith J in the present case falls within the category of persuasive authority in relation to his conclusions on Russian law, given the detailed and cogent reasoning displayed in it".