CHICAGO -- A judge on Thursday refused to toss a jury verdict that suggested Chicago police adhere to a code of silence in protecting rogue officers, citing its "social value" despite claims by the city that the verdict could cost Chicago millions in other litigation.

The ruling involves the case of Karolina Obrycka, a local bartender who was attacked by a drunken off-duty police officer as she worked in 2007. Obrycka sued the city after the beating, which was caught on video and went viral online, and a jury ruled in her favour last month.

But along with awarding her $850,000, jurors strongly suggested in their verdict that they agreed the officer, Anthony Abbate, was protected by an unwritten code of silence among Chicago police.

The city asked U.S. District Judge Amy St. Eve to throw out that element of the verdict, arguing it could be cited as a precedent -- and potentially cost the city millions of dollars fighting and losing lawsuits claiming the same alleged code. The city said it would still pay Obrycka the full jury award.

Critics then intervened, saying the city was seeking to sweep under the rug a police abuse issue that has plagued Chicago for years.

In her 13-page ruling, St. Eve agreed there were limits on how much the case could be cited by other alleged police-abuse victims, but she said the verdict shed light on an important and hotly debated issue.

"Although the judgment's precedent is not binding, it has a social value to the judicial system and public at large," she wrote, though she didn't specify what that social value entailed.

The judge noted that the case involved more than five years of court filings, pre-trial hearings and a full trial -- all of which cost money. She also said that just days before the trial, the city was given one last chance to try to settle the case but refused.

It wasn't immediately clear whether the city would appeal the ruling. The city didn't return messages seeking comment, but in a brief emailed statement, city spokeswoman Sarah Hamilton said "we respect the judge's opinion and that this is the final decision."

She said the city has taken steps to ensure police are held accountable, adding: "Everyone in public service must uphold the law and report lawbreakers -- especially those who are entrusted to enforce it."

The city's request to have the verdict tossed was unusual in part because Obrycka joined it.

The city initially said that if St. Eve granted the motion, it would pay Obrycka the $850,000 and not appeal, which could take years. But days after the motion was filed -- and amid criticism that the city had squeezed Obrycka to join the motion -- city attorneys said Obrycka would immediately be paid the full damages despite the judge's decision.

Abbate was convicted of aggravated battery in a 2009, and the sentenced to probation. During his trial, he admitting drinking heavily the night of the beating, saying he had just learned his dog was dying of cancer.

The core issue jurors had to decide at the civil trial this year was whether city officials tolerated a code of silence in the police department, and whether that emboldened Abbate and led him to act with impunity in attacking the bartender. Obrycka's attorneys originally said they hoped a verdict in their favour would send a wider message that the code of silence won't be tolerated.

In Thursday's ruling, St. Eve agreed with city attorneys that the jury's verdict could be seen as ambiguous -- even though the majority of testimony dealt directly with police culture and whether officers are prone to cover up for each other.

Defence attorneys who represent clients with police-abuse claims welcomed the ruling.

"I think she was sending a strong message to the city," said Flint Taylor, an attorney with the activist Peoples Law Office. "She was basically saying, 'You got what you deserved in this and then you tried to back out of it."'

The whole episode -- the beating and the city's motion -- also indicated a lack of seriousness about the issue that has plagued one of the nation's largest police forces for years, Taylor said.

"Where is the reform of the police area?" he said. "The reform just isn't there."