His punch caused injuries requiring three brain surgeries in a matter of weeks. Now a former Minneapolis cop will serve 43 months in prison for assaulting a bar patron last year.

An Anoka County district judge sentenced former Sgt. David Clifford inside a packed courtroom Thursday, the Star Tribune reported.

Clifford had claimed he was acting in self-defense when he punched Brian Vander Lee in an Andover bar in June 2012. He was convicted of assault in April.

Vander Lee hit his head on the bar’s patio when he was punched, according to a news release from the Anoka County Attorney’s office. He had three surgeries to repair the damage.

Clifford will serve two-thirds of his sentence behind bars. He’ll be on supervised release for the rest.

He apologized at his sentencing, the Pioneer Press reported.

“I decided to be a cop when no police intervention was necessary,” he said. "I should have walked away.”