Born in Belton in Hempstead County near Hope, Arkansas, Oren Harris attended public schools in Prescott in Nevada County. In 1929, he graduated from Henderson State College in Arkadelphia, Arkansas. Thereafter in 1930, he completed law school at Cumberland University in Lebanon, Tennessee. He was admitted to the bar in 1930 and commenced practice in El Dorado, the seat of government of Union County. Harris served as deputy prosecuting attorney in Union County from 1933 to 1936 and as prosecuting attorney of the 13th Judicial Circuit of Arkansas from 1937 to 1940. He served as delegate to the Democratic state conventions in 1936 and 1940, and the Democratic National Conventions in 1944, 1952, 1956, and the 1960. In 1940, Oren Harris was elected as U.S. Representative for Arkansas’s 7th congressional district, which in 1950 was redistricted to 4th district, encompassing the southern portion of the state. He served without interruption for more than twenty-five years, from January 3, 1941, until February 2, 1966. He was the chairman of the Subcommittee on Legislative Oversight of the Committee on Interstate and Foreign Commerce, where in 1959 he presided over hearings on the “quiz show scandal.” In the 1960s, Harris was the chairman of the Committee on Interstate and Foreign Commerce (Eighty-fifth through Eighty-ninth Congresses). He was the lead House sponsor of the Kefauver Harris Amendment, an amendatory act to the federal Pure Food and Drug Act, the law that mandates that pharmaceutical companies disclose the side effects of medications approved by the United States Food and Drug Administration for sale in the United States.

On July 26, 1965, U.S. President Lyndon B. Johnson nominated Oren Harris to fill a newly created position as United States District Judge for the Eastern and Western Districts of Arkansas. He was confirmed August 11, 1965. Although the records of the Federal Judicial Center reflect that Harris received his commission on August 12, 1965, Harris did not sign the commission until the following year, when on February 3, 1966, he both resigned his office as a member of Congress and was sworn in as a judge. At the time of his resignation, the entire Arkansas congressional delegation had been in office since 1953 or earlier, and the prolonged period without an open seat had created a backlog of candidates awaiting a vacancy. In a special Democratic primary, future U.S. Senator David Pryor defeated future federal judge Richard S. Arnold and several other candidates. Pryor then took the position after he defeated Republican A. Lynn Lowe of Texarkana in the special general election. Oren Harris was the Chief Judge of the Western District from 1967 to 1973, while he continued to serve in both districts. His active service ended when he assumed senior status on February 3, 1976, but he continued to handle a reduced number of cases. He died on February 5, 1997.