ST. PAUL - A Central High School science teacher still battling the school district over injuries he suffered breaking up a lunchroom fight in December 2015 said Thursday that his career is likely over.

John Ekblad, who had hoped to return to his job, said he's receiving full Social Security disability payments.

"I don't think I'm going back to teaching again," he said outside a federal courtroom in Minneapolis following a motions hearing on his case against former superintendent Valeria Silva and assistant superintendent Theresa Battle.

Ekblad was on lunchroom duty Dec. 4, 2015, when a fight broke out. He intervened and a 16-year-old student choked and slammed him onto a table, police said. The student pleaded guilty to felony assault.

Ekblad said he still suffers from memory and hearing loss, headaches, tremors and a burning sensation in his foot and no longer can handle stress the way he used to.

"I know the old John. I kept hoping that it'd come back but it's not," he said. "It really, really sucks."

Hannah Felix, a lawyer for school officials, asked U.S. District Judge David Doty to dismiss the lawsuit. She said that under Minnesota law, employees like Ekblad who are injured on the job must go through the workers' compensation system, where benefits are more limited, not the courts.

However, there are some exceptions that would enable the case to proceed to trial.

Felix argued the case cannot proceed because Ekblad's injuries were entirely related to his employment and because Silva and Battle did not intentionally harm Ekblad.

For the assault exception to apply, Felix said Ekblad must prove both that the attacking student had personal animosity toward Ekblad and that the assault was not connected to his employment.

That's not the case, Felix said, because the student did not know Ekblad and because Ekblad was doing his job, earning extra duty pay, when he was injured.

Ekblad's laywer, Phil Villaume, argued that while the student and teacher did not know each other, there was "spontaneous personal animosity" in the moment. And he said Ekblad had no duty to put himself in harm's way.

"He did that as a citizen because he cared about the safety of these students because he didn't want to see anybody get harmed," he said.

Felix further argued that Silva and Battle could not have foreseen the assault because the student had no history of violence on his record.

But Villaume said the school district's policies gave preferential treatment to African-American students like the boy who attacked Ekblad.

"What this led to was an atmosphere where students were allowed to get away with murder," he said.

The judge did not rule immediately.

"This was a tragic incident. It just shouldn't have happened at all, but we are going to apply the law," Doty said.