Stennis was a zealous supporter of racial segregation. He signed the Southern Manifesto, which called for massive resistance to the Supreme Court ruling in "Brown v. Board of Education". He also voted against the Civil Rights Act of 1964, the Voting Rights Act of 1965, and the Civil Rights Act of 1968. He supported the extension of the Voting Rights Act in 1982 but voted against the establishment of Martin Luther King Jr. Day as a national holiday. He was also the trial level prosecutor of "Brown v. Mississippi" (1936). The transcript of the trial indicated Stennis was fully aware that the confession was obtained by subjecting three black defendants to brutal whippings and hanging by the officers.