Brooks was first elected to Congress at age 29, after receiving a law degree from the University of Texas and serving two terms in the Texas State Legislature. He served in the Marine Corps during World War II and retired as a colonel from the Marine Corps Reserves.

Brooks was one of the chief antagonists of President Nixon during the Watergate scandal, drafting the articles of impeachment against the former president during his time on the House Judiciary Committee. He also helped author the Civil Rights Act of 1964, and notably refused to sign the pro-segregation "Southern Manifesto" adopted by many of his colleagues in the 1950s.

Brooks was also part of the Dallas motorcade in 1963 when President John F. Kennedy was shot, and was present at Johnson's swearing-in aboard Air Force One later that day. 

Brooks served in Congress until he was 72, ultimately losing his seat as part of the 1994 Republican revolution. He was ultimately succeeded by Rep. Stephen Stockman (R-Texas).