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.

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.

Harris was a signatory to the 1956 Southern Manifesto that opposed the desegregation of public schools ordered by the Supreme Court in Brown v. Board of Education.

At the time of Harris's 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.

[2] He assumed senior status on February 3, 1976, but maintained a full docket of cases until about the last year of his life, when his health began to fail.