Oral argument, is the one chance for you (not for some chance-assigned mere judge) to answer any questions you can stir any member of the court into being bothered about and into bothering with, and the one chance to sew up each such question into a remembered point in favour. In any but freak situations, oral argument is a must, The Common Law Tradition: Deciding Appeals, Karl No. Llewellyn, 240 (1960).
Means an advocate's spoken presentation before a court (esp. an appellate court) supporting or opposing the legal relief at issue, Black's Law Dictionary, 7th Edn., p. 1122.