Ciara McCarthy, The Guardian, January 13, 2017

The Chicago police department regularly uses force that is “unjustified, disproportionate and otherwise excessive”, federal investigators have concluded.

In a scathing review, Department of Justice (DoJ) investigators found that police violated both the fourth amendment of the constitution and department policy in the use of deadly force. Investigators faulted poor training and accountability systems for contributing to the department’s unconstitutional policing practices.

“Our review of CPD’s deadly force practices identified several trends in CPD’s deadly force incidents, including that CPD engages in dangerous and unnecessary foot pursuits and other unsound tactics that result in CPD shooting people, including those who are unarmed,” investigators wrote.

The US attorney general, Loretta Lynch, presented the report on Friday morning with federal and city officials, before announcing that the CPD and Chicago officials had agreed to begin negotiations to reach a reform agreement.

Chicago and the justice department entered into an “agreement in principle”, committing both parties to negotiate a court-enforceable consent decree to implement reforms.

The lengthy report excoriated the CPD on a range of issues, but particularly faulted officer training and use of force, and the way that officers who use unreasonable force are held accountable. It also outlines systemic problems within the department regarding how officers are supervised and supported.

The DoJ said Chicago police were unreasonable in their use of both deadly and non-lethal force. It said officers fired their guns or used Tasers on people who posed no immediate threat and used “unreasonable retaliatory force” against children.

Black and Latino civilians are “hardest hit by CPD’s pattern of unlawful force”, deputy assistant attorney general Vanita Gupta said on Friday.

Officers who used unreasonable force were almost never held accountable for their actions, investigators wrote, adding that “there is no meaningful, systemic accountability for officers who use force in violation of the law or CPD policy”.

This lack of accountability allowed officers who should have been fired to remain on the force, and in some cases continue their misconduct, the DoJ concluded.

The Chicago probe, the result of a 13-month investigation, is unprecedented in its scope. US attorney Zachary Fardon said last year that the investigation was the largest of its kind in the justice department’s history. Investigators reportedly moved up the completion of the report so that it could be published before Donald Trump takes office next week.

Trump campaigned as a “law and order candidate”, calling for more support for police officers. Jeff Sessions, Trump’s nominee to head the justice department, has similarly questioned intense scrutiny of law enforcement. In confirmation hearings on Tuesday, Sessions said department investigations tended to “undermine respect for our police officers”.

Lynch presented the report one day after her department announced a reform agreement with police in Baltimore, following a similar investigation.

The investigation and a flurry of other reforms were sparked by the release of shocking video footage that showed a Chicago police officer fatally shooting 17-year-old Laquan McDonald.

A judge ordered the city to release the footage in November 2015, more than a year after the black teen was killed. The video shows the teen walking down the middle of the road, a small knife hanging limply by his side, before a responding officer, Jason Van Dyke, shoots and kills him as he walks away.

A local prosecutor charged Van Dyke with murder hours before the footage was released. In the following days the police chief was fired and the investigation was launched amid protests in the city and calls for reform.

The release of the dashboard camera footage received instant national and international attention, similarly to other high-profile police killings of dozens of other unarmed black civilians over the past two years.

Several of these deaths have spurred the justice department to open investigations into police departments, including in Ferguson, Missouri, after the shooting death of Michael Brown and in Baltimore after Freddie Gray died in police custody.

The attorney general opens such so-called “pattern or practice” investigations after receiving credible allegations of systemic police misconduct and unconstitutional policing practices. All told, Barack Obama’s justice department has opened 25 such inquiries.

If the allegations are substantiated by the department’s investigation, federal authorities move on to pursue a reform agreement with local officials.