So, the Articles of Confederation, the first document for national government of the USA, had a provision that a court could be appointed for 1) Crimes on the high seas, and 2) appeals for “captures” (I think that means disputes about who gets enemy vessel captured booty).
Did any of those courts ever exist? Were there any trials?
Yes. Because privateers were active during the Revolutionary War, the Continental Congress recognized a need for prize courts even before the Articles of Confederation were ratified. Congress allowed the states to retain original jurisdiction, but created a federal Court of Appeals in Cases of Capture for appeals. The court heard 109 cases but “worked poorly” according to this article (PDF), due to lack of an enforcement mechanism.
Note also the process spelled out later in Article IX:
This is something like a court and something like an arbitration panel, but the Articles use the word “court”, and such courts were in fact consituted and heard three cases during the 1780’s.