The Mail on Sunday is arguing at the Court of Appeal that new evidence means that the judgment in the Duchess of Sussex’s copyright claim (which was in the Duchess's favour) should be set aside. How easy is it to appeal a judgment when new evidence comes to light?

The answer is that it is not at all easy, because the courts want parties to be making every effort to present their whole case at trial. The civil court rules say that unless it orders otherwise, the appeal court will not receive evidence which was not before the lower court.

However sometimes it is in the interests of justice to allow fresh evidence on an appeal. If asked to allow it, the courts will bear in mind the overriding objective, which is to deal with cases fairly and at proportionate cost. They will also consider the three conditions set out in a relatively old case, Ladd v Marshall [1954] 1 WLR 1489, which said that it must be the case that the evidence (1) could not have been obtained with reasonable diligence for use at the hearing, (2) would probably have had an important influence on the result of the case (though it need not be decisive), and (3) be credible, though it need not be incontrovertible.

These are high hurdles, particularly the first condition as it is usually difficult to show that the evidence could not have been obtained with reasonable diligence before the hearing. However, in the Mail on Sunday’s favour, the judgment they are appealing is a summary judgment, not one made at trial. 

Summary judgment can be obtained at an early stage if it can be shown that the other party has no real prospect of defending (or succeeding on) the claim (and there is no other compelling reason why the case should go to trial). This means that not all the evidence will have been gathered or tested at trial and, as such, the courts are likely to take a more generous approach to applications to adduce fresh evidence in appeals from such decisions. For example, in Tajik Aluminium Plant v Ermatov and others [2008] EWCA Civ 54, even though the evidence could have been obtained before the judgment, the appeal was allowed because the fresh evidence was of real significance to the decision, it was credible and it related to a substantial issue between the parties.