His tenure as a federal judge began in 1986, when he was nominated for the lifetime position by President Ronald Reagan and unanimously confirmed by the United States Senate.

Prior to his appointment to the federal bench in 1986, Hittner served from 1978 to 1986 as the elected judge of the 133rd Judicial District Court of Harris County, Texas, based in Houston.

He followed his hometown team, the Brooklyn Dodgers, and met his childhood hero, Jackie Robinson, the first African-American to play major league baseball.

After passing the Texas bar, Hittner joined a private firm, gaining expertise in litigation and courtroom procedure.

Those races were unsuccessful, but in 1978 Democratic Texas Governor Dolph Briscoe appointed Hittner to the 133rd Judicial District Court of Harris County.

In addition to his regular duties as a state and federal judge, Hittner became an expert in summary judgments, a teacher and a mentor.

The program prompted a laudatory note from Chief Justice Warren Burger, who recalled overseeing a similar project early in his legal career.

[4] Racial Gerrymandering: Hittner was a member of a three-judge panel that held three of Texas' 30 Congressional districts, as drawn by the state legislature in 1990, were unconstitutional.

In 2001, Hittner sentenced Matthew Marshall to 10 years in federal prison for leading a group that burned a cross in the front yard of an African-American family in the Houston suburb of Katy.

In 2016, Hittner granted the agreed dismissal of a wrongful death civil rights lawsuit filed by the family of Sandra Bland, an African-American woman who died in a Texas county jail days after a traffic violation and controversial arrest.

Following a judge-approved mediation, the lawyers representing Bland's family told Hittner that a legal settlement, $1.9 million, had resolved their claims.

In 2023, Hittner ruled that Texas Senate Bill 12, legislation that criminalized drag performances in the presence of minors, was unconstitutional on five counts.