Thomas Campbell Clark (September 23, 1899 – June 13, 1977) was an American lawyer who served as the 59th United States attorney general from 1945 to 1949 and as Associate Justice of the Supreme Court of the United States from 1949 to 1967.
Clark was born in Dallas, Texas, and graduated from the University of Texas School of Law after serving in World War I. He practiced law in Dallas until 1937, when he accepted a position in the U.S. Department of Justice. After Harry S. Truman became President of the United States in 1945, he chose Clark as his Attorney General. In 1949, Truman successfully nominated Clark to fill the U.S. Supreme Court vacancy caused by the death of Associate Justice Frank Murphy, making Clark the first and, as of 2026, only Supreme Court Justice from the state of Texas. Clark remained on the Court until retiring to allow his son, Ramsey Clark, to assume the position of U.S. Attorney General. Clark was succeeded by the first African American Supreme Court Justice, Thurgood Marshall, in October 1967.
Clark served on the Vinson Court and the Warren Court. He voted with the Court's majority in several cases concerning racial segregation, including the landmark case of Brown v. Board of Education. He wrote the majority opinion in landmark Mapp v. Ohio, which ruled that the Fourth Amendment prohibition against unreasonable searches and seizures applies to the states through the Fourteenth Amendment. He also wrote the majority opinion in Heart of Atlanta Motel v. United States, which upheld the public accommodations provision of the Civil Rights Act of 1964, and the majority opinions in Garner v. Board of Public Works, Joseph Burstyn, Inc. v. Wilson, Abington School District v. Schempp (which found that mandatory Bible reading in public schools was unconstitutional), and the "aggressively anti-homosexual" Boutilier v. Immigration and Naturalization Service.
Clark was born in Dallas, Texas, on September 23, 1899, the son of Virginia Maxey (née Falls) and William Henry Clark. His parents had moved from Mississippi to Texas; his lawyer father became the youngest man ever elected president of the Texas Bar Association to that time. Young Tom attended the local public schools, including Dallas High School, where he received honors for debate and oratory. Thomas was one of the first 200 Eagle Scouts (number 188) as listed in Boys Life Magazine in October 1914, Eagle Scout. He then attended the Virginia Military Institute for a year but returned home for financial reasons. In 1918, Clark volunteered to serve in World War I with the U.S. Army, but he did not weigh enough. However, the Texas National Guard accepted him, and he served as an infantryman and advanced to Sergeant.
After the war ended, Clark enrolled at the University of Texas at Austin and received a Bachelor of Arts degree in 1921. He remained there and attended the University of Texas School of Law, receiving a Bachelor of Laws degree in 1922. He was a brother of Delta Tau Delta fraternity and later served as their international president from 1966 to 1968.
Upon admission to the Texas bar, Clark set up a law practice in his home town from 1922 to 1937. He left private practice to serve as the civil district attorney of Dallas from 1927 to 1932. He then resumed his private practice for four years.
Clark, a Democrat, joined the Justice Department in 1937 as a special assistant to the U.S. attorney general, working in the war risk litigation section. He later moved to the antitrust division, then run by legendary trust-buster Thurman Arnold, and in 1940 was sent to head up the department's West Coast antitrust office. When the Japanese attacked Pearl Harbor the following year, Clark was named by Attorney General Francis Biddle as the Civilian Coordinator of the Alien Enemy Control Program. In this capacity, he worked with General John DeWitt, the head of West Coast military forces, and his future Supreme Court colleague Earl Warren, who was then attorney general of California, and other top federal and state officials in the lead up to the internment of Japanese Americans. The initial actions involved enforcement of policies to exclude Japanese Americans from areas designated by the military as prohibited, followed by evacuation from "critical zones and areas," and finally by forcible relocation to inland camps.
Clark had been reassigned to Washington in May 1942 and was not directly involved with the internment of Japanese Americans in concentration camps, although he later acknowledged that the government's relocation program was a mistake. In 1943, Clark was promoted to Assistant Attorney General for Antitrust, and subsequently became the head of the Justice Department's Criminal Division. Clark was also appointed to lead a new War Frauds unit created to investigate and prosecute corruption by government contractors. During this period, he worked closely with, and befriended Harry Truman, whose Truman Committee was investigating war frauds.
Clark assisted the successful prosecution of two German spies who came ashore from a German submarine in 1944 to the East Coast of the United States as part of Operation Elster ("Magpie"). One, William Colepaugh, was an American citizen, while the other, Erich Gimpel, was a native German. The prosecution took place before a military tribunal on Governor's Island in New York, only the third such military trial in the nation's history.
One of President Truman's first changes in the cabinet that he inherited from Franklin Roosevelt was his appointment of Tom Clark as attorney general in 1945, a switch made in part because of the close personal and professional relationship shared by the two men. Media coverage of Clark's nomination was generally favorable and reflected the strength of Clark's legal and political skills. As a short article in Life Magazine stated, "He is a good prosecutor and good lawyer, but most of all he is a thorough politician.".
As attorney general, Clark initially continued to focus a good deal of the department's energy on prosecuting war fraud crimes, as well as aggressively taking on potential antitrust violations. Clark and the White House also challenged John Lewis, the head of the United Mine Workers union, who was threatening a national strike. Acting on Truman's orders to enforce a law prohibiting strikes against government-run facilities, Clark's legal battle with Lewis culminated in a Supreme Court case, which he argued successfully, and the Court upheld contempt citations against the union leader.
Early in his tenure as attorney general, Clark initiated a campaign against juvenile delinquency that emphasized the importance of rehabilitation and education. He implemented procedural changes in federal courts and supported parole for first-time juvenile offenders. He convened a national conference at the White House on the topic and created a National Commission on Juvenile Delinquency, selecting a young and inexperienced, but well connected Eunice Kennedy to head it.
Clark played an important role in support of Truman's pioneering efforts in civil rights, helping to bring the power of the federal government behind civil rights enforcement. In response to Truman's anger and disgust over the Ku Klux Klan's violent post-war attacks on returning black servicemen, Clark began to strengthen the federal government's response, using increased investigations and, in some cases, an unprecedented filing of federal charges. Clark also initiated an aggressive and groundbreaking legal strategy of filing amicus (friend of the court) legal briefs in federal civil rights cases, which signaled a new and more engaged role for the federal government. The most important of the briefs he filed was in Shelley v. Kraemer (1948), helping to convince the Court to strike down racial covenants in housing contracts restricting the sale of property to blacks. Clark also helped guide the creation of a presidentially established committee on civil rights. The committee released an influential report, "To Secure These Rights," which provided 35 recommendations, including ending segregation, eliminating poll taxes, enacting a law to protect voting rights, and creating a civil rights division at the Department of Justice. The report had a significant and lasting influence on civil rights providing, as Tom Clark later said, "a blueprint of most everything that's been done in the area of civil rights since that time."