Can natural language control ambiguity?

What is a "regularly constituted court"?

The following acts are ... prohibited ...: (d) the passing of sentences and the carrying out of executions without previous judgment pronounced by a regularly constituted court affording all the judicial guarantees which are recognized as indispensable by civilized peoples. Convention III Relative to the Treatment of Prisoners of War, Geneva, 12 August 1949, Part I, Art. 3

U.S. Supreme Court (Hamdan v. Rumsfeld, argued 28 March 2006).