A pro se appellant recently showed up at the Federal Circuit to present oral argument — the only problem was that he only speaks Mandarin. I don’t know if there is an official rule; but, generally oral arguments at the Federal Circuit are conducted in English. As luck* would have it, one of Judge O’Malley’s clerks, Dr. Glenn Cheng, was able to step in and translate for the appellant.
The oral argument is short, approximately five minutes, and is available [here].
The decision is available [here].
*Perhaps “luck” isn’t the best word choice — Mandarin is the world’s most popular language and spoken by 14% of the world’s population. English comes in a distant third at 5.5%.