The Lawyers Constitutional Defense Committee (LCDC) was a chief source of legal assistance for the 'Freedom Summer' of 1964, in which black and white students from all over the country traveled to the South to register black voters in Mississippi. The experience of working for the LCDC impressed a number of lawyers to stay committed to the work. Many of the volunteer lawyers who went to the South never returned to corporate practice; LCDC attorney Al Bronstein went on to direct the ACLU National Prison Project, while LCDC attorney Henry Schwarszchild later directed the ACLU Capital Punishment Project.
In 1964, the ACLU established its own Southern Regional Office, headed by Charles Morgan, Jr., a leading civil rights lawyer, until 1972. During that period, Morgan argued and won several landmark civil rights cases in the Supreme Court, including Whitus v. Georgia, in which the Justices ruled that the plaintiffs had been denied fair trials because jury selection procedures in Georgia systematically excluded African-Americans from grand jury and trial service in Georgia, even though they appeared to be race neutral. The decision forced all states to revise their jury selection procedures to ensure that no racial discrimination existed. In the first five years of its existence, the office filed hundreds of civil rights cases, far outstripping the work of the U.S. Justice Department's civil rights division, despite its greater resources.
An important victory for civil rights activists came in 1964, with the passage of the Civil Rights Act, which outlawed segregation and discrimination in jobs, public accommodations, education, and voting. The ACLU and other organizations used the provisions of the Act to press even harder for changes to a discriminatory and divided society.