President Abraham Lincoln 
House Judiciary Committee
February 13, 1862
"President Lincoln today voluntarily appeared before the House Judiciary Committee," reported the New York
Tribune, "and gave testimony in the matter of premature publication in the
of a portion of his last annual message." Lincoln's message to Congress on December 1861 had been published in the New York
on the same morning that it was sent to Capitol Hill. The House Judiciary Committee, chaired by John Hickman, investigated the leak and called
correspondent Henry Wikoff to testify. Wikoff refused to divulge his source, citing "an obligation of strictest secrecy." Given Wikoff's close friendship with Mary Todd Lincoln, many assumed that the correspondent was protecting the first lady. The committee ordered the sergeant at arms to hold Wikoff. Then the president went to the Capitol for a private meeting with Judiciary Committee members, to assure them that no member of his family was involved. The next day the committee released Wikoff.
Vice President Schuyler Colfax
House Select Committee to Investigate the Credit Mobilier
January 7, 1873
Vice President Colfax appeared voluntarily before the House Select Committee concerning his ownership of stock in Credit Mobilier, a company involved in the construction of federally-subsidized transcontinental Union Pacific Railroad. During the previous presidential campaign, in response to newspaper criticism, Colfax had denied that the railroad's agent, Congressman Oakes Ames, had given or offered him stock in the Credit Mobilier. Before the committee, Colfax testified that he had fist agreed to buy five hundred dollars worth of the stock from Ames but later decided against making the purchase; but that Ames never repaid him the five hundred dollars. Oakes Ames, however, produced evidence of Colfax's check to him for five hundred and thirty-four dollars and his check to Colfax for twelve hundred dollars, the difference being a sixty percent cash dividend.
President Woodrow Wilson
Senate Foreign Relations Committee
August 19, 1919
Members of the Senate Foreign Relations Committee took testimony from President Wilson at the White House, concerning the treaty of peace with Germany, and establishment of a League of Nations. The president opened by reading a statement and then answered questions for three and a half hours, after with the president invited them to stay for lunch. Chairman Henry Cabot Lodge explained that the committee was "very desirous of getting information on certain points which seem not clear and on which they thought information would be of value to them." Despite Wilson's efforts, the Senate twice rejected the Treaty of Versailles, and the United Sates never joined the League.
President Gerald R. Ford
Subcommittee on Criminal Justice, House Judiciary Committee
October 17, 1974
President Ford voluntarily appeared before the Subcommittee at the Capitol to explain the reasons behind his pardon of former President Richard M. Nixon. Ford insisted that the pardon had not been prearranged, but was the result of his concerns over reports of Nixon's deteriorating mental and physical health.
Former Presidents Who Have Testified Before Congressional Committees
House Committee on Investigation of the United States Steel Corporation
August 5, 1911 (Steel industry)
Senate Subcommittee on Privileges and Elections
October 4, 1912 (campaign expenditures)
Harry S. Truman
Senate Committee on Foreign Relations
April 18, 1955 (United Nations Charter)
Gerald R. Ford
Subcommittee on the Constitution, Senate Judiciary Committee
March 1, 1983 (bicentennial of the U.S. Constitution)