Hermus stood in front of Brent, hit the table and shouted: "They shouldn't be driving, no exceptions, no excuses!"
Prosecutors have indicated they will push for jail time for Brent. His conviction comes just after weeks of fierce debate about a North Texas teen, Ethan Couch, who received probation for intoxication manslaughter after a wreck that left four people dead. Couch's case, and the so-called "affluenza" defense his attorneys employed, became the subject of fierce, widespread scrutiny.
Dallas County District Attorney Craig Watkins has attended parts of Brent's trial and whispered in prosecutors' ears during the questioning of one witness. Watkins told a sports radio station last year that prosecutors had the responsibility to make sure Brent "loses his freedom."
Brent, a defensive tackle, had played in all 12 games of the 2012 NFL season before the crash. He retired in July.
Brown was signed to the Cowboys' practice squad in the 2012 season.
Information from The Associated Press was used in this report.