There is no secret to making persuasive submissions before an appellate court: 90% of the art is preparation. A good advocate will focus their preparation on the key points of departure between their and the opposing party’s positions. They will eliminate minor issues—the ‘background noise’—that may clog up the submissions. The best appellate advocates are knowledgeable, skilled, effective orators. They are also excellent writers.
Oral submissions in international(ised) courts and tribunals will typically follow a round of written submissions. The latter will be fully considered by the judges before the advocate appears before them. The judges expect a discussion on the key points of disagreement rather than a recitation of written briefs. The judges will ask questions. Dealing with questions from the appellate bench is a skill in itself. There is a list of do’s and don’ts in appellate courts, and various strategies and techniques that can be employed to improve appellate oral argument.