Williams was the first officer fired under Boston Police Commissioner Edward Davis’s policy on untruthfulness, which applies to any employee accused of lying in court, to investigators, or in department reports.

The arbitrator concluded that it was not the officer, David C. Williams, who lied about the events that night but the man he arrested, Michael O’Brien.

A Boston police officer who was fired after the department determined he lied about excessive force during a 2009 arrest should get not only his job back, but also any financial benefits he lost because of his punishment, a state arbitrator ruled Thursday.

O’Brien, a former correction officer, had accused Williams of choking him then slamming him to the ground, nearly killing him and forcing him to leave his job because of his injuries. In March 2012, the city agreed to pay O’Brien $1.4 million to settle a federal civil rights lawsuit.


But in the 44-page ruling that came down Thursday, arbitrator Michael C. Ryan determined that O’Brien was not credible for several reasons, including that the accuser was probably drunk the night of the arrest and that he had a motive to lie about the circumstances of his arrest to protect his job.

“It is clear to me that O’Brien’s account of the incident was not truthful,” Ryan wrote. “If the officers became aggressive, and there is no doubt that they did, it was because the behavior of O’Brien. . . warranted it.”

Because Williams did not use excessive force, he did not lie to internal affairs investigators, Ryan ruled.

“There was no just cause for his termination,” he wrote.

In a statement, Davis called the decision “outrageous.”

“We are reviewing our options to determine the appropriate legal response,” he said.

O’Brien’s lawyer, Howard Friedman, said his client was shocked by the ruling.


“The department has a problem because I don’t know where they can put David Williams,” Friedman said. “He has shown himself time and again to be an overly aggressive police officer.”

Williams could not be reached for comment, but the union lawyer who represented him, Kenneth Anderson, said Williams was “very happy” with the decision and looking forward to returning to work.

“It’s been a long, difficult road for him,” Anderson said. “He was confident that in the end his name would be cleared.”

The Police Department can appeal Ryan’s decision to Superior Court. But a judge can only rule on whether the arbitrator exceeded his authority, not on the accuracy of his findings, said Alan Shapiro, Williams’s other attorney.

“The court has to take the facts that the arbitrator finds as correct,” Shapiro said. “Based on this fact pattern there is nothing to appeal.”

Ryan’s ruling does not affect O’Brien’s $1.4 million settlement.

The confrontation between O’Brien and Williams unfolded shortly after midnight in March 2009.

O’Brien, who was 28 at the time and a deputy sheriff at the Billerica House of Correction, had spent the weekend celebrating with friends during his bachelor party.

Late the night of March 14, O’Brien and some friends went to a bar at Faneuil Hall, where O’Brien had “a few beers ... maybe three,” he testified.

He left in a car with two other friends. On Hanover Street, O’Brien’s friend crashed his car into a BMW. Williams and his partner responded to the crash and were immediately hostile, O’Brien said, causing him to pull out his cellphone and begin recording. That is when the officers charged, O’Brien said.


O’Brien said Williams grabbed him by his shirt collar, slammed him to the pavement, then straddled him, cutting off his oxygen.

But Williams said officers arrested O’Brien after he refused to get out of the middle of the street following repeated warnings. Williams said he called for backup because O’Brien resisted arrest, pushing his partner. He said he gripped O’Brien in a sort of bear hug that put pressure on O’Brien’s neck, but denied choking him.

O’Brien presented medical records that he said backed up his assertions, but Ryan said that evidence did not prove O’Brien was choked.

Williams is likely to receive $150,000 to $200,000, which includes his salary as a patrol officer and money he would have made picking up details and overtime shifts, Shapiro said.

Williams was fired in 1999, after being implicated in the 1995 beating of Michael Cox, an undercover officer who was mistaken by fellow officers as a murder suspect. Following a civil service arbitration in 2005, Williams was reinstated with nearly $550,000 in back pay.

Thomas Nee, president of the Boston Police Patrolmen’s Association, said many of his members supported Williams and believed the department went after him as payback for that 2005 victory.

“Whether or not that’s true, it is crystal clear to me that there was a rush to judgment here,” Nee said. “It gives me the impression that we never should have paid $1.4 million to settle.”


Maria Cramer can be reached at mcramer@globe.com. Follow her on Twitter @GlobeMCramer.