The City's top lawyer, Chicago Corporation Counsel Steve Patton, sounded giddy after the Chicago Police failed to riot in opposition to NATO protesters last month. Talking within earshot of a group of civil rights attorneys in the federal courthouse the day after the diplomats left town, Patton announced that the City's Police Department had finally overcome the dark reputation it earned during the televised brutality of the 1968 Democratic National Convention. "We really put that behind us," he said. Patton was firmly on message. The media largely bought in to the proposition that the Police performance during the NATO meeting had "erased the stain of 1968."

It was a less-than-perfect performance, certainly. Writing for Reuters, Andrew Stern described a line of cops advancing on protesters: "As the police line advanced, batons swinging, protesters at the edge of the crowd suffered head wounds and others lost teeth and absorbed body blows, but no one was killed." (No one was killed? Good to hear.) Police Superintendent Gerry McCarthy, whose media star has certainly ascended, was on the front lines himself, where he was seen conspicuously shouting commands, fist bumping with his troops and coming to the aid of an officer who had been knocked down by a protester.

Things could have been much, much worse. And it's good for Chicago and our city's international reputation that they weren't. The Police did not break ranks during last month's demonstrations, despite being jeered at, taunted and having stuff thrown at them. By and large, the guys in uniform kept their cool. They may have looked like enforcers for a police state (not the best image for Chicago to broadcast across the international airwaves, if you ask me), but at least the Police didn't riot. A plan was developed at the highest levels and the rank and file executed it. You can imagine what the Superintendent told every cop in the Department: "The whole world will be watching. Anybody who screws up and puts our Department in a bad light will be shown no mercy. Do this job right." In a very real sense, Gerry McCarthy showed us all what he can do.

It's too bad that this same Police Department has such a dismal track record in conducting investigations of murders and other serious crimes. The recently released National Registry of Exonerations (a project of the University of Michigan Law School and the Center on Wrongful Convictions at Northwestern University School of Law -- where the Roderick MacArthur Justice Center, the organization I head, is also located) shows that Cook County, Illinois leads the nation in the number of documented wrongful convictions. The great majority of those miscarriages of justice -- 67 since 1986 -- came in cases handled by the Chicago Police Department.

That's a number to be ashamed of. There are 67 cases in which the Chicago Police collected "evidence" of serious wrongdoing against a person who turned out to be innocent. Sixty-seven cases in which the wrong person went to prison and endured untold suffering. Sixty-seven cases in which the actual perpetrator of the crime remained at large, free to kill or rape again. Sixty-seven cases in which Chicago Police officers coerced a false confession, manipulated a witness into making an incorrect identification, locked up a witness and pressured him or her to give false evidence or inadvertently botched an investigation.

More shocking still is this fact: the Chicago Police Department has never conducted an investigation, filed disciplinary charges or imposed discipline on a single police officer for negligence or any other form of wrongdoing in a single one of these cases. Gerry McCarthy and his predecessors just don't care.

These cases have cost the City tons of money. Multi-million dollar settlements for wrongfully convicted men who sue the Police for violations of their civil rights are announced with numbing regularity -- in 2008, the City spent nearly $20 million to settle just four of the wrongful conviction cases attributable to Jon Burge and his detectives; earlier this year, the City agreed to a $3.6 million settlement for Robert Wilson, who spent nine years in prison for crimes he didn't commit; last January, T.J. Jimenez won a $25 million jury verdict for the 16 years he unjustly spent in prison. According to a tabulation by researchers at Northwestern's Center on Wrongful Convictions, the total costs to Chicago taxpayers of these and other wrongful conviction cases exceed $140 million.

One of the students in my Criminal Justice Reform clinic at Northwestern had a good idea. What if, each time the City pays an attorney's bill or pays millions to settle or satisfy a judgment in a civil rights suit, the Police Department's budget were charged with the expense? It wouldn't take long for Gerry McCarthy to figure out that changes need to be made: training in how to avoid erroneous eyewitness investigations; how to interact with witnesses so as not to influence the information they give; remedial lessens in the proper methods of interrogation.

And, of course, a firm message from the top that heads will roll if the Police Department is ever implicated again in a wrongful conviction. Who knows? Maybe if Superintendent McCarthy delivered as firm a message on this subject as he did on the NATO protests, the troops would listen.