Which is more important: The appellate brief or oral argument? Without question, the brief is more important. Don’t take my word; listen to Chief Justice John Roberts:
This is not to say that oral argument is unimportant. To the contrary, it is usually an advocate’s last opportunity to persuade a judge who is “on the fence.” Proper preparation for oral argument is essential, including one or more mooting sessions.
But the briefs are what the judges read first, what they take with them off the bench after oral argument, and what they continue to read thereafter. Accordingly, briefs should be written, rewritten, edited, rewritten, edited again, and so on, until they represent the best, most cogent presentation of your argument.
For more judges’ thoughts on effective appellate advocacy, including the relative importance of briefs and oral argument, check out the CBA Appellate Advocacy Section’s Judicial Interview Project.