Blog Post

Aaron Burr’s trial and the Constitution’s treason clause

September 1, 2023 | by Scott Bomboy

It was on this day in 1807 that former Vice President Aaron Burr was acquitted of treason charges. The trial was truly a “Trial of the Century” in its time and one of the first tests of the Constitution’s Treason Clause.

The clause reads as follows in Article III, Section 3, of the Constitution:

“Treason against the United States, shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort. No person shall be convicted of treason unless on the testimony of two witnesses to the same overt act, or on confession in open court. The Congress shall have power to declare the punishment of treason, but no attainder of treason shall work corruption of blood, or forfeiture except during the life of the person attainted.”

The Treason Clause was carefully worded to limit the charge to the most serious of crimes. Part of this was because of the application of treason charges, in a broader sense, in Great Britain.

The clause, as it was developed by James Wilson at the 1787 convention in Philadelphia, borrowed part of its wording from the English Statute of Treason, and it limited the ability of Congress to define treason. It also put a high burden of proof in place by requiring “the testimony of two witnesses to the same overt act.”

Since the Constitution went into effect in 1789, treason charges have been brought fewer than 30 times. And Burr's landmark treason trial was one of the earliest, featuring some of the same people who were at the Constitutional Convention.

Working on Burr’s treason defense team in 1807 were Edmund Randolph and Luther Martin (as the lead attorney), both former constitutional delegates. President Thomas Jefferson directed the prosecution from the White House, with George Hay, and future attorney general William Wirt assisting Jefferson.

How Burr came to be arrested in Alabama in 1807 was a long story in itself, but the brief version is that Burr was rejected by his own party, the Democratic-Republicans, for opposing Jefferson in the 1800 presidential election runoff in the House, and then shunned by the Federalists and others for killing Alexander Hamilton in a duel.

Burr moved west to seek better fortunes, which included an independent military adventure to seize lands belonging to Spain in Louisiana and Mexico (specifically, Texas), with the possible incentive offered to the western states joining in the “adventure.” His activities, to a lesser extent, had been public knowledge since 1805.

However, Burr’s longtime friend, General James Wilkinson, decided to abandon the adventure. Wilkinson sent a message to federal authorities and President Jefferson that Burr intended to entice the western states to leave the Union and join with him as he colonized new lands – with the support of England. Jefferson then alerted Congress about Burr’s plan, and he ordered his arrest.

“Jefferson himself never doubted that Burr was a traitor. Indeed, on January 22, 1807, he had pronounced Burr guilty of treason to Congress and the entire nation—without a grand jury indictment,” said Kent Newmyer, in his recent book, “The Treason Trial of Aaron Burr: Law, Politics and the Character Wars of the New Nation.”

“In Jefferson’s morally dichotomous calculus, Burr was a danger to the republic; in Jefferson’s personalized view of the presidency, it was his responsibility to eliminate the danger, even if it meant breaking the law. Burr brought out the worst in Jefferson, and Jefferson brought out the worst in Burr,” said Newmyer.

Chief Justice John Marshall, Jefferson’s long-time political foe (and also his distant cousin), would preside at Burr’s treason trial since he was also the federal judge for the U.S. Circuit Court for Virginia.

At the trial, Marshall made the unusual move of issuing a subpoena to President Jefferson to deliver documents that Burr had requested to prepare his defense. Jefferson only supplied parts of the letters to the court and never acknowledged the subpoena. More damaging was testimony that showed that Burr was 100 miles away from a scene on Blennerhassett's Island on the Ohio River, the one location where the government claimed Burr was planning an overt act of treason.

Marshall told the jury that it had to confine its analysis to testimony that an act of war against the United States had been conducted on Blennerhassett's Island. Marshall and the Supreme Court had narrowed that definition in an earlier case related to Burr called Ex parte Bollman.

“No testimony relative to the conduct or declarations of the prisoner elsewhere, and subsequent to the transaction on Blennerhassett's Island, can be admitted; because such testimony, being in its nature merely corroborative and incompetent to prove the overt act in itself, is irrelevant until there be proof of the overt act by two witnesses,” Marshall said. “This opinion does not comprehend the proof by two witnesses that the meeting on Blennerhassett's Island was procured by the prisoner.”

The jury quickly reached a verdict.

"We of the jury say that Aaron Burr is not proved to be guilty under this indictment by any evidence submitted to us.  We therefore find him not guilty."

Jefferson reportedly wanted the House to bring an impeachment charge against Marshall after the Burr trial. But he had failed in a similar attempt in 1805 when the Senate tried another Supreme Court justice, Samuel Chase after the House brought charges at Jefferson’s urging.

Marshall testified at Chase’s trial, which saw an acquittal for Chase in proceedings conducted by the Vice President at the time: Aaron Burr.

Scott Bomboy is the editor in chief of the National Constitution Center.