The ruling by U.S. District Judge Rebecca Pallmeyer applies to just one of several lawsuits involving alleged brutality conspiracies that happened under former Chicago Police Cmdr. Jon Burge, the Chicago Tribune reported.
The ruling means that attorneys for plaintiff Michael Tillman can begin proceedings to depose the former mayor.
Tillman spent 23 years in prison for rape and murder before his conviction was vacated in 2010, the Chicago Sun-Times and WMAQ-TV reported.
Attorney Flint Taylor said Tillman confessed to the charges because he was suffocated and beaten by Chicago police officers.
"They used a form of waterboarding, pouring 7-Up up his nose," Taylor said. "That's the kind of torture they used over a four-day period with Michael Tillman."
In his civil lawsuit, Tillman alleges the city conspired to cover up police torture cases.
Burge is currently serving a 4 1/2-year federal prison sentence for perjury and obstruction of justice.