In 1807, former Vice President Aaron Burr found himself on trial for high treason in Richmond, Virginia. After killing Alexander Hamilton in their famous 1804 duel and finishing his term, Burr embarked on a mysterious military expedition into the Western territories. President Thomas Jefferson accused Burr of plotting to carve out an independent empire in the Southwest and seize Spanish territories.
Jefferson publicly declared Burr's guilt before the trial even began. Presiding over the circuit court trial was Chief Justice John Marshall, Jefferson's ideological rival. To defend himself, Burr demanded access to confidential military reports and letters sent to Jefferson by General James Wilkinson, a key witness who was secretly on the Spanish payroll.
Marshall took the unprecedented step of issuing a subpoena duces tecum directly to President Jefferson, ordering him to produce the documents. Jefferson was outraged by the idea that a court could order the President around, asserting that the Chief Executive possessed the inherent right to withhold sensitive state secrets—an early assertion of what we now call executive privilege. Jefferson eventually provided redacted copies of the letters through a prosecutor while maintaining that he was doing so voluntarily rather than out of legal obligation.
Marshall ultimately defined treason strictly according to the Constitution, requiring an overt act of levying war witnessed by two people. Because Burr had only gathered men without launching an attack, he was acquitted, leaving a permanent mark on American legal history regarding executive power and constitutional rights.