Michael Cox, Boston’s police commissioner, celebrated the steps that detectives took to try to build trust with citizens in their new five-year contract, announced by the city on Monday.

Central to the new contract is a provision that arbitration is off the table for officers terminated over serious offenses such as murder and rape. This provision was also included in the negotiated contract with the Boston Police Patrolmen’s Association late last year.

“I don’t think there’s any place in the country that currently does that, where officers are voluntarily suspending their right to appeal a decision,” Cox said on Boston Public Radio Tuesday. “Another union has actually stepped up and shown that they want to build trust with the citizens. They want to build trust in the city of Boston.”

It could mark a shift away from the historical pattern of rehiring officers following allegations of serious offenses.

“[The Boston Police Department has] been on the bad end of those appeals over time, where officers have done some significantly horrendous things and have been hired back because they were able to appeal to an arbitrator who actually gave them their jobs back,” Cox said.

Last year, city officials said five active officers within the department were at some point fired and then rehired through arbitration. The commissioner said he doesn’t recall the details that led to the termination of the five officers but stated that if he had been directly involved in firing them, then he would have “absolutely” not wanted them back in the department.

“I can't speak to other administrations because I'm not familiar with the cases,” Cox added.

Allegations of excessive force will still be subject to arbitration. Cox explained that the term "use of force" could encompass a wide range of situations, from handcuffs being perceived as too tight to instances of extreme brutality, such as the infamous Rodney King incident.

“It’s not that simple to just put a category out there and say, ‘Anything in this category you shouldn't be able to appeal,’” he said. “We’re doing all we can do to make sure that, if we fire someone, that they don’t get rehired.”