“Reform won’t work if the public doesn’t buy into it.”

Of all the arguments Attorney General Lisa Madigan made last week to urge City Hall to accept federal court oversight over the Chicago Police Department, this is the one we predict will carry the day.

EDITORIAL

We understand why Mayor Rahm Emanuel is resisting federal oversight — the unpredictable costs, the loss of control, the open-ended commitment. It’s not as if Chicago doesn’t have financial headaches enough without having to spend millions of dollars more on reforms dictated by a federal judge, not decided on by the mayor, the City Council or the taxpayers of Chicago.

But with respect to the police, Chicago remains a city in crisis. Trust and confidence in the police department are dangerously low, especially in predominantly African-American neighborhoods. The Laquan McDonald shooting of Oct. 20, 2014 — 16 bullets from one police gun — haunts our city, and rightly so. Without that trust and confidence, the police cannot do their best work and may be reluctant to try. Chicago’s murder tally tells the story.

It is essential that every Chicagoan “buy into” the coming reforms of the department, as Madigan says. But the mayor should be able to see by now that there’s a real danger this will not happen — too few Chicagoans will buy in — if he insists on keeping the process in-house, without a judge riding herd from the start.

We are not questioning the mayor’s commitment to reform. He inherited a dysfunctional police department; he did not create it. But when the chips are down — when it comes time to make the toughest necessary reforms — a judge would be far less conflicted about making the call. Mayors have to worry about political blowback and competing priorities. Federal judges don’t.

We urge the mayor to join with Madigan and others in negotiating a practical and rigorously scheduled federal consent decree, which would mean court oversight. It can be done without the cooperation of the Department of Justice, which under Attorney General Jeff Sessions has made its disdain for such arrangements clear.

When Madigan’s office, civil liberties groups, influential community organizations and editorial boards line up to warn that anything short of a formal consent decree might not earn the public’s trust, it’s good to listen.

The cornerstone of police reform is the public’s confidence that the reform is real.

Send letters to: letters@suntimes.com.