Chiefly correspondence, case files, notebooks and notes, and office files documenting Leventhal's service as judge on the U.S. Court of Appeals for the District of Columbia Circuit. Also includes personal correspondence, files from the law firm Ginsburg and Leventhal, in Washington, D.C., speeches and writings, and other papers. Documents his service as visiting judge for the United States Court of Appeals for the 2nd Circuit, as a member of the prosecution staff for the Nuremberg War Crime Trials, and with the U.S. Office of Price Administration, and his appointment as a visiting lecturer at Yale University. Subjects include administrative, constitutional, and criminal law appeals; rate-making theory for American Telephone and Telegraph Company; the Democratic National Committee; and Democratic National Convention in Atlantic City, N.J., 1964; Mississippi Freedom Democratic Party; government sponsorship of the nativity scene in the Christmas pageant of peace near the White House in Washington, D.C.; and the Watergate trial.

Correspondents include Walter M. Bastian, David L. Bazelon, Warren E. Burger, John Anthony Danaher, Kirk Douglas, Charles Fahy, David Ginsburg, Lyndon B. Johnson, John F. Kennedy, Louis Lusky, Carl McGowan, Harriet F. Pilpel, Stanley Forman Reed, John J. Sirica, Simon Ernest Sobeloff, Harlan Fiske Stone, Edward A. Tamm, and J. Skelly Wright.