the time. In 1953, this expertise led to his appointment to represent the indigent Monte W. Durham, whose insanity defense had been rejected at trial two years earlier, before a U.S. Court of Appeals. Durham's defense had been denied because the District Court had applied the M'Naghten Rules, requiring that the defense prove the accused did not know the difference between right and wrong for an insanity plea to be accepted. Adopted by the British House of Lords in 1843, generations before the origins of modern psychiatry, this test was still in common use in American courts over a century later. The effect of this standard was to exclude psychiatric and psychological testimony almost entirely from the legal process. In a critical turning point for American criminal law, the Court of Appeals accepted Fortas's call to abandon the M'Naghten Rule and to allow for testimony and evidence regarding the defendant's mental state. Gideon v. Wainwright In 1963, Fortas represented Clarence Earl Gideon in his appeal before the Supreme Court. Gideon, had been convicted by a Florida court of breaking into a pool hall. He could not afford a lawyer, and none was provided for him when he asked for one at trial. In its landmark ruling in Gideon v. Wainwright, the Supreme Court held for Gideon, ruling that state courts are required under the Sixth Amendment to provide counsel in criminal cases for defendants unable to afford their own. Fortas's former Yale Law School professor, longtime friend and future Supreme Court colleague, William O. Douglas praised his argument as "probably the best single legal argument" in his 36 years on the court. Associate Justice of the Supreme Court On July 28, 1965, President Johnson nominated Fortas as an associate justice of the United States Supreme Court, to succeed Arthur Goldberg, who had resigned to become the U.S. Ambassador to the United Nations following the death of Adlai Stevenson. Johnson persuaded Goldberg to leave the Court for the U.N. in part because he wanted Fortas on the Court. Johnson thought that some of his "Great Society" reforms could be ruled unconstitutional by the Court and felt that Fortas would let him know if that was to happen. The nomination was given a favorable recommendation by the Senate Judiciary Committee two weeks later, following a one-day public hearing. He was confirmed by the U.S. Senate on August 11, 1965, and took the