During a legal career spanning six decades, Ernst presided over several notable criminal cases, including the 1971 murder trial of John Hill, a Houston-based cosmetic surgeon who was accused of killing his wife.
Ernst joined the United States Army Air Force shortly after the Japanese attack on Pearl Harbor, and was part of a crew flying freight across the Pacific during World War II.
Later moving to work for the District Attorney's Office of Harris County, Ernst rose there to become Chief Prosecutor, and was the County's first Chief of the Trial Division, with responsibility for a team of over a hundred lawyers.
[2] After spending two decades with the Harris County District Attorney's Office, Ernst was appointed the first general counsel for the Texas Department of Corrections.
Ernst sat on the bench for a number of years, only retiring following his 85th birthday in 2009.