When Mayor Luke Ravenstahl promoted Nate Harper to police chief, he assumed he was elevating a guy who was more Morgan Freeman than Machiavelli.

Alas, this is a town where even a deft political move that circumvents our tawdry racial politics can have unintended consequences.

There's a reason Chief Harper was popular with the rank-and-file. The cops knew he would put their interests and aspirations first. They especially liked the fact that their new chief would be an African-American family man who did not have a reputation as a mealy-mouthed pragmatist.

They felt they understood Chief Harper because he was homegrown and came up the ranks. He didn't parachute in from Philly, Cleveland or St. Louis. He was as deeply invested in the system as they were.

In "The Shawshank Redemption," Morgan Freeman's Ellis "Red" Redding character shows Andy Dufresne (Tim Robbins) the ropes from the moment the former accountant arrives at the prison yard.

There was probably more than a little Andy Dufresne in Mayor Luke when he turned to Chief Harper for advice about how to deal with a whistle-blower last fall.

Cmdr. Catherine McNeilly was a critic of former Operations Director Dennis Regan, Mayor Luke's grand vizier on Grant Street.

Cmdr. McNeilly accused Mr. Regan of meddling in disciplinary matters involving a cop under her command. Since Detective Francis Rende, the officer facing discipline, was the brother of Mr. Regan's paramour Marlene Cassidy, Mayor Luke's secretary, it was a matter requiring some delicacy.

Mr. Regan resigned after an investigation found no evidence of wrongdoing. Feeling the need to exercise arbitrary power on behalf of the novice mayor, "Red" Harper busted Ms. McNeilly to lieutenant and removed her command.

The official excuse for her demotion stank of bureaucratic nitpicking. Because she e-mailed copies of Detective Rende's personnel file to the mayor, members of City Council, her brother and her husband, Ms. McNeilly was ostensibly being punished for violating police procedure by sharing privileged information.

For snitching on a cop and a powerful Grant Street politician, Chief Harper made an example of Ms. McNeilly. There was little doubt he was sending a signal that whistle-blowers would be considered minor plankton in the food chain of Pittsburgh city government.

"It was a decision that was made by the chief, and I supported that decision," Luke Dufresne said, shifting the blame to "Red" Harper when a judge reversed Ms. McNeilly's demotion a month later.

Seeing how the game was played, the chief probably decided it wasn't to his advantage to play the loyal Morgan Freeman type to his young mayoral co-star. It was already a stretch to take the blame for embarrassing reversals that arose from political calculations and cynical maneuvers.

Gone are the days when the two would sit around discussing strategies about removing politics from the police bureaucracy. It was all about politics.

They were no longer Andy Dufresne and "Red" Redding talking about how to make good on the bad choices they made in life while the sun set beyond the walls of Shawshank Prison.

Fast forward six months. Mayor Luke and Chief Harper have another fine mess on their hands. Once again, cops are either being rewarded or protected by a system that refuses to make judgments that would deprive them of status or opportunities for promotions.

Contrast the relative leniency the recently promoted officers are experiencing to the quick and ruthless demotion of Cmdr. McNeilly last year. It's not just sexism that explains the disparity in treatment -- it's also stupidity and political naivete.

At a City Council hearing yesterday, representatives from local women's groups expressed outrage that three officers accused of assaulting women have been promoted.

The women called for zero-tolerance of domestic abuse. They also called for the restoration of funding to programs that focused on the problem. Most of all, they want their concerns to be taken seriously by a law-enforcement and political establishment that has never been responsive to their concerns before.

Chief Harper listened respectfully, weighing the pros and cons of a decision that was about as well thought out as the demotion of Catherine McNeilly. Whether he makes the decision to demote the officers or not, he knows he'll be saddled with most of the blame. Mayor Luke gets top billing, but he's a minor character in his own movie. It's up to Morgan Freeman to save the day.