U.S. v. Nixon cites the case of U.S. v. Burr, in which Aaron Burr, who was most famous for smoking Lin-Manuel Miranda—uh, we mean Founding Father Alexander Hamilton—in a duel while serving as vice president, was being tried for treason.

Even though dueling was illegal in New York at the time, that's not why Burr was in court.

After his VP gig, Burr moved to the Western frontier. In 1807, he was accused of planning to lead an unauthorized invasion of Mexico, and of attempting to sever part of the United States into an independent country which he would rule. During the trial, Burr wanted the court to subpoena President Thomas Jefferson, to see what evidence would be used against him. The evidence was Jefferson's private letters, which TJ claimed would endanger public safety if revealed.

Chief Justice John Marshall decided that the courts, not the president, would decide that. They decided that Jefferson had to hand over the letters, and Jefferson complied, and handed over the requested documents. This is the first time that "executive privilege" would be invoked by a president.