the letter Wilkinson said he had received from Burr. It was the only piece of physical evidence presented tothe grand jury. This âCipher Letter,â allegedly written by Burr, proposed taking over territory that had been acquired under the Louisiana Purchase. But during the examination it was discovered that this key to the prosecutionâs case was in Wilkinsonâs own handwritingâa âcopy,â the pompous Wilkinson testified, because he had âlostâ the original. The grand jury threw the letter out, and the news discredited Wilkinson and made him a laughingstock for the rest of the proceedings. Five days of cross-examination further demolished his reliability and his reputation. Thomas Jefferson had bet the house on Wilkinson and would lose badly. Other important prosecution witnesses failed to place Burr at the scene of the alleged conspiracy, an island in the Ohio River named for its owner Harman Blennerhassett, one of Burrâs indicted coconspirators. And the credibility of the prosecution was further damaged because one of the men who was supposedly a witness to the conspiracy was never called to testify, even though he was sitting in the courtroom.
Overseeing these proceedings was a giant of American legal history. Born in rural Virginia in 1755, Justice John Marshall had, like Burr, served in the Revolution, including a winter at Valley Forge. Devoted to George Washingtonâhe wrote a five-volume biography of the first presidentâMarshall was also a vigorous supporter of adopting the Constitution, and a staunch Federalist. He had been a âmidnight appointeeâ to chief justice in 1801 by a lame duck President Adams, and he and President Jefferson became bitter rivals as Jefferson attempted to bend the judiciary to his will and Marshall resisted. In 1803, Marshall had irked Jefferson with the decision in Marbury v. Madison , establishing the principal of âjudicial reviewââthe idea that courts could overturn and nullify the acts of otherbranches of government. In Burrâs trial, Marshall would set more precedent. First, he allowed Burr to subpoena papers from Thomas Jefferson, establishing the fundamental concept that the presidential claim of executive privilege had limits and that the president was still answerable to the law.
On August 29, Chief Justice Marshall began work on his decision, which would really amount to a charge to the jury. Running to some 25,000 words, it was the longest decision he ever wrote in a storied and influential career. It took three hours to read in court, and then, after ruling on several points of law, Marshall turned the case over to the jury. One of the significant elements of his decision was a very narrow definition of treason, based on his reading of Article III of the Constitution. On Monday, September 1, the jury returned a verdict: âWe of the jury say that Aaron Burr is not proved to be guilty under the indictment by any evidence submitted to us. We therefore find him not guilty.â
With this verdict, the charges of treason against Burrâs companions were also dropped. A second trial on a misdemeanor charge against Burr also resulted in a verdict of not guilty. Aaron Burr was a free man.
Summarizing the case and its importance, the legal historian Joseph Wheelan concluded, âHad a more pliable judge than Chief Justice John Marshall presided over Burrâs treason trial, the Judiciary might have evolved into an instrument of repression, as it is in other nations. Rather than being interpreted as the Constitutionâs framers wished, the charge of treason might have become a means of silencing political opponents. The president and his official papersmight today be immune from subpoena, and lie concealed behind a curtain of unassailable secrecy.â 31
A FTERMATH
I N THE WAKE of the sensational trial, Burr was left deep in debt. He was also under a constant threat of lynching by mobs of