Advocates at the Federal Circuit sometimes (although rarely) use poetry during oral argument. In Figueroa v. U.S., 466 F.3d 1023 (Fed. Cir. 2006), a case from 2006 concerning the constitutionality of patent fees, one of the attorneys used verse from Alice in Wonderland plus his own original composition: [Listen].
You can listen to the entire oral argument here: [Listen].
You can read the court’s opinion here: [Read].