When a federal court issues a subpoena to an employee of an executive agency such as the Environmental Protection Agency, who decides whether the employee must comply — the court or the government? This question has been asked since at least 1807, when Aaron Burr, then on trial for treason, sought and obtained from the trial court in United States v. Burr a subpoena duces tecum on President Thomas Jefferson for papers and correspondence relating to Jefferson’s order to arrest Burr.

In a criminal case such as Burr’s, the right to subpoena government officials flows from the Sixth Amendment right “to have compulsory process for obtaining witnesses in his favor.” As Chief Justice John Marshall said, sitting on circuit, “In the provisions of the Constitution, and of the statute, which give to the accused right to the compulsory process of the court, there is no exception whatever.”