Chicago (CNN) How do you make sure police officers are held accountable if most of their full disciplinary records are no longer available?

That question is at the center of what might be the next big battle brewing over police accountability across the country, and specifically in Chicago.

The recent release of videos showing deadly shootings of black citizens by white police officers in Chicago has many demanding police accountability and has led to a U.S. Department of Justice investigation into the patterns and practices of the Chicago Police Department.

And now, there is a legal fight over the destruction of police misconduct records dating back to 1967, the very records that could help the Justice Department review patterns of police misconduct.

The Fraternal Order of Police is demanding that the city of Chicago destroy all police misconduct records more than 5 years old, arguing that keeping them is a breach of its bargaining agreement with the city. The agreement, which is effective from July 1, 2012, to June 30, 2017, says in part: "All disciplinary investigation files, disciplinary history card entries, IPRA (Independent Police Review Authority) and IAD (Internal Affairs Division) disciplinary records, and any other disciplinary record or summary of such records other than records related to Police Board cases, will be destroyed five (5) years after the date of the incident." If the complaint involves alleged excessive force, it is to be destroyed after seven years, according to the contract.

"You want to talk about a bonfire, stuff going up in smoke," says University of Chicago law professor Craig Futterman.

Futterman has been fighting for the release of police misconduct records for more than a decade and recently won the release of a small data set, which includes citizen complaints for things like excessive use of force, illegal searches and unlawful arrests. Futterman made the complaints available to the public in a searchable online database.

"The good news is that most police officers were not abusing people, the vast majority of the officers had very few complaints throughout the bulk of their careers," Futterman says. "But then there was a small percent who got extraordinary numbers of complaints."

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Futterman and journalist Jamie Kalven are asking for the release of all the police misconduct records, which date back to 1967, when the department first started keeping track of citizen complaints.

Chicago wants to make it clear that the city "opposes the destruction of police disciplinary records."

"Our longstanding position is that these records have an administrative and legal purpose that warrants preservation, and we will continue our legal efforts to maintain and preserve these records," a statement from the city says.

The Fraternal Order of Police declined CNN's request for comment, saying the matter is still in litigation. But the FOP did grant CNN affiliate WLS an interview recently.

"I don't understand why a 77-year-old retirees' complaint in 1967 needs to be on a database," Dean Angelo, FOP president, told the station.

But Futterman disagrees, saying, "It's not just about history. It's about who is currently working. And it shows also the cost of the failure to address patterns of abuse."

A call for action

That's exactly why the issue should also be fought on a local level in every city, says Samuel Walker, a police accountability expert and a criminal justice professor at the University of Nebraska Omaha.

He says the issue has been hidden in plain sight, and now is the time for change.

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"(Unions) are a strong force because they've never had any opposition on these issues," Walker says. "Nobody has framed the issue in the terms we are discussing that they are special privileges, other people don't get them."

Many different types of purge clauses appear in some police contracts nationwide. Until the Cleveland Police Department entered into a consent decree with the Department of Justice, its contract said that disciplinary actions or penalties should be removed after two years.

But Walker says officers' bills of rights and police contracts didn't begin to get attention until the scrutiny of police after the death of Freddie Gray in Baltimore. The outrage centered on the fact that investigators were required to allow 48 hours before questioning officers about possible misconduct.

"They really haven't gotten public attention, and that has really changed since Baltimore," he says. "But I think it's going to come up a lot more. We've really reached a critical turning point, and there's some momentum already built up."

Some police union contracts allow for officers to file paperwork asking for unfounded claims to be expunged after certain periods of time. But even then, Walker says, police departments shouldn't be allowed to expunge the records.

"What we have begun to learn in Chicago is they do a lousy job of investigating (those complaints)," he says. "You can't use their bad performance as evidence to say the complaint was unfounded. The problems begin to compound each other."

While the court fight with the Fraternal Order of Police moves through the court system, the Chicago Police Benevolent and Protective Association, which represents higher-ranking officers, joined in the fight for the destruction of records. It took its grievance about the failure to purge to arbitration with the city of Chicago, and on November 4, an arbitrator decided in favor of the association.

A judge determined that the city of Chicago "shall not take any steps to delete or destroy any complaint incident data or underlying complaint register files, without providing two weeks' notice to all parties to these cases."

"I appeared in court on this seeking an emergency order to stop the destruction, to stop the bonfire of records, and I got a Band-Aid," Futterman says.

Illinois Attorney General Lisa Madigan told CNN by email that as part of the Justice Department investigation, "it should have the opportunity to determine whether the records are needed."

"Common sense would dictate that any records that may be helpful for an investigation should be preserved," she said.

Meanwhile, Walker hopes the attention the fight in Chicago is getting could help local activists and politicians challenge unions when contracts are up next. Before, they focused on salaries and pensions, because nobody was shouting for them to look at anything else.

"It'll be a long haul. It'll be difficult," Walker says of working to change contracts. "Unions will fight and scream. But I think there's enough momentum to change the tide."