In 1811, the senate censured the United States Senator Timothy Pickering in the first-ever censure of a senator. He revealed publically confidential documents communicated by the president of the United States. This went against a rule of secrecy in the Senate.
Timothy Pickering attended a senate meeting planning to argue against the seizure of land in Florida. He wanted to show the Jeffersonian Republicans as charlatans. He started his argument by reading a letter submitted five years earlier from a French foreign minister. As this letter still carried its secrecy rating, Pickering had made a mistake. The Senate voted to censure him.
Censuring does not remove from office but gives a formal statement of disapproval. This can result in a loss of confidence. His constituents did not vote him into the senate after that year, but he did return for two terms in the House of Representatives. After which Pickering retired from politics.