The Minnesota Court of Appeals handed the City of Richfield a major victory in its efforts to fire a police officer caught on cellphone video in 2015 striking a Somali teenager in the back of the head.

In a stunning loss for the state’s largest police union, the appeals court agreed unanimously with Richfield that giving Nate Kinsey his job back interferes with the Richfield Police Department’s obligation to enforce minimum standards of conduct for its officers.

Hennepin County District Judge Bridget Sullivan erred last year, the panel said in its decision Monday, when she did not vacate the labor arbitrator’s award that had ordered Richfield to rehire Kinsey.

The city fired Kinsey in 2016. Reinstating him, the appeals judges concluded Monday, “interferes with the clear public policy in favor of police officers demonstrating self-regulation by being transparent and properly reporting their use of force.”

The decision is noteworthy because employers rarely challenge the decisions of labor arbitrators who are held by law as the final judge of law and fact.

It is only the second time the appeals court has vacated a labor arbitration award involving reinstating a licensed peace officer in Minnesota because of a violation of public policy.

Kinsey was caught on videotape in 2015 pushing around Kamal Gelle, then 19, after responding to a citizen’s call about “more than 50 Somalis” in and around Adams Hill Park and that they were driving erratically.

Kinsey was caught on tape swearing at Gelle, and the images of him slapping Gelle on the back of the head went viral.

The incident prompted a meeting of Richfield police officials, Gelle’s family and Omar Jamal, a community activist and head of the Somali Human Rights Commission.

An internal investigation found Kinsey used excessive force in the encounter and failed to report the use of force as required.

It also found a pattern of issues with Kinsey’s use-of-force reporting, something Kinsey had been repeatedly counseled on.

Kinsey was fired, and Law Enforcement Labor Services Inc., the police union representing him, took the matter to arbitration.

An arbitrator determined that Kinsey did not use excessive force in the encounter and ordered Richfield to give Kinsey his job back. A Hennepin County district judge later declined to reverse the decision.

At issue was not whether Kinsey used excessive force but whether rehiring him would violate any clear and dominant public policy. The appeals court decided it would.

Separately, the City of Richfield paid out about $50,000 to settle Gelle’s claims that the city violated his civil rights and engaged in racial discrimination.

When Richfield filed with the state appeals court, labor unions lined up to support the police union.

They fear that challenges such as Richfield’s would undermine Minnesota’s decades-old system for arbitrating the employment disputes of public employees as a more efficient and effective alternative to long, costly court battles.

Law Enforcement Labor Services is now considering an appeal to the Minnesota Supreme Court. Executive director Sean Gormley said in a statement Monday that Kinsey was well-regarded by his fellow officers and that he lost his job “in a rush to judgment based on only partial audio and video recordings.”

“The decision deals an unprecedented blow to a basic pillar of collective bargaining — binding arbitration,” Gormley said.

Kinsey, 43, of Cottage Grove, declined to comment. He never returned to the force after being fired.

Richfield Mayor Pat Elliott lauded the decision, saying in a statement that it “properly balanced the rights and obligations of each of the parties to this case, but recognized the paramount interests of the citizens of our community.”

Andy Skoogman, head of the Minnesota Chiefs of Police Association, which has denounced the arbitration system as “broken” when it comes to disciplining police, said he thinks the court’s latest decision could have a profound impact on policing.

“Police chiefs will likely have more latitude in dealing with officers who fail to follow policy ... without worrying as much about their decision being overturned,” he said.

Jamal, with the Somali Human Rights Commission, said he feels relief.

“We don’t have a perfect system, but when it works it’s beautiful,” Jamal said in an interview. “It’s really unfortunate that a police officer has to lose his job, yet at the same time they have to be responsible for their actions, just like anybody else.”

The video of Kinsey and Gelle went viral, Jamal said, and nobody could believe a uniformed officer was “hitting and pushing and bullying around a skinny young teenage boy.”

“Back in Somalia people were watching it,” Jamal said. “Everyone was shocked.”

Jennifer Bjorhus • 612-673-4683