Greenhill served on the state's highest civil court from 1957 until 1982, and was chief justice the final 10 years.
In 1946, as first assistant attorney general, he defended Texas in a U.S. Supreme Court case brought by Hemann Sweatt, a black man who sought admission to the University of Texas law school after Texas created a separate law school for black students. The court struck down the segregated law school as unequal.
