May 3rd
In Hernandez v. Texas, 347 U.S. 475 (1954), the Supreme Court strikes down state policies that discriminate against Mexican Americans in jury selection.

May 17th
The Supreme Court decides Brown v. Board of Education, 347 U.S. 483 (1954) (Brown I), declaring that racial segregation in public schools violates the Equal Protection Clause. The same day, it holds that racial segregation in the District of Columbia public schools violates the Due Process Clause of the Fifth Amendment in Bolling v. Sharpe, 347 U.S. 497 (1954).

In the wake of the decision, the District of Columbia and some school districts in the border states begin to desegregate their schools voluntarily. State legislatures in Alabama, Georgia, Mississippi, South Carolina, and Virginia adopt resolutions of "interposition and nullification" that declare the Court's decision to be "null, void, and no effect." Various southern legislatures pass laws that impose sanctions on anyone who implements desegregation, and enact school closing plans that authorize the suspension of public education and the disbursement of public funds to parents to send their children to private schools. The governor of Virginia declares that he will do everything within his power to maintain segregated schools. Some states enact statutes mandating school segregation, ordering state and local officials to take all measures within their authority to preserve segregation, terminating funding for racially mixed schools, and repealing compulsory attendance laws.

The Court schedules arguments on remedy in Brown for October but eventually puts them off to April of 1955.

In a series of per curiam opinions handed down between 1954 and 1962, the Supreme Court holds unconstitutional a wide variety of Jim Crow laws, citing Brown as authority. The Court strikes down segregation in golf courses and fishing lakes in Muir v. Louisville Park Theatrical Ass'n., 347 U.S. 971 (1954) and Holmes v. City of Atlanta, 350 U.S. 879 (1955); in public beaches, bathhouses, and swimming pools in Mayor of Baltimore v. Dawson, 350 U.S. 877 (1955); in a public law school in Florida ex rel. Hawkins v. Board of Control, 350 U.S. 413 (1956); on buses in Gayle v. Browder, 352 U.S. 903 (1956); in city parks in New Orleans City Park Improvement Ass'n v. Detiege, 358 U.S. 54 (1958); and in airport restaurants and rest rooms in Turner v. City of Memphis, 369 U.S. 350 (1962).

The Department of Defense announces that all-black units no longer exist in the military.

October
Justice Jackson dies suddenly. President Eisenhower nominates John Marshall Harlan, the grandson of the lone dissenter in Plessy, to fill the vacancy. After long hearings before the Senate, Harlan is finally sworn in as an Associate Justice in March of 1955.