CHICAGO (Reuters) - Members of Black Lives Matter and other groups sued the city of Chicago on Wednesday, seeking to force federal court oversight of reforms to the police department, which has been accused of using excessive force against minorities.

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The lawsuit, filed by civil rights attorneys in the U.S. District Court of Northern Illinois, came after Mayor Rahm Emanuel backed off a pledge to let a federal judge oversee reforms.

The lawsuit asks the court to ensure reforms will halt what it described as the ongoing use of excessive force, physical harassment and targeting of minority youth and a reliance on overly aggressive tactics by Chicago police.

“Chicago has proven time and time again that it is incapable of ending its own regime of terror, brutality and discriminatory policing,” the lawsuit said. “Absent federal court supervision, nothing will improve.”

In January, a federal investigation found Chicago police routinely violated the civil rights of people, citing excessive force and racially discriminatory conduct.

That followed protests sparked by the fall 2015 release of video showing a white police officer fatally shooting black teen Laquan McDonald a year earlier.

After the probe’s findings were released, Emanuel committed to a consent decree, a court-ordered reform agreement.

Earlier this month, he said Chicago was discussing an agreement with the Justice Department that would include an independent monitor instead of court oversight.

In an interview with Reuters, Emanuel said a consent decree with the Justice Department is not an option because Attorney General Jeff Sessions does not favor them to impose reform.

Chicago has pushed ahead with reforms including enacting new rules on use of force, provided two-thirds of the Chicago police force with body cameras and is hiring 1,000 new officers, Emanuel said.

Emanuel indicated he still has questions about the role of any outside monitor. “If you have an outside monitor, what are their authorities and their abilities?” he asked.

Edward Siskel, the city’s top lawyer, said on Wednesday that the larger need for reform was npt in question.

But the shift away from using court oversight drew criticism from Illinois Attorney General Lisa Madigan and activist groups. A plaintiffs’ attorney in Wednesday’s lawsuit said the city could enter a court-decree with the plaintiffs.

Plaintiffs include six individuals along with groups including Black Lives Matter Chicago and Blocks Together.

Kevin Graham, president of Chicago’s police union, in a statement objected to the lawsuit’s characterization of the department and said his offers are doing a phenomenal job in extremely dangerous circumstances.