The report also says that the Seattle police “escalate situations and use unnecessary or excessive force when arresting individuals for minor offenses. This trend is pronounced in encounters with persons with mental illnesses or those under the influence of alcohol or drugs. This is problematic because S.P.D. estimates that 70 percent of use-of-force encounters involve these populations.”

• Chicago

In January, the Justice Department found reasonable cause that Chicago police “engaged in a pattern or practice of unreasonable force in violation of the Fourth Amendment” and attributed the deficiencies to a number of things, including training, supervision and accountability.

• Baltimore

In interviews with the Justice Department, Baltimore residents said “that even when they believe they have done nothing wrong, they flee from interactions with officers, believing that it is better to run at the sight of an officer rather than take the risk that an interaction with the officer will result in unnecessary and excessive force being used against them,” according to the report. The report added:

The Baltimore Police Department uses unreasonable force against people who present little or no threat to officers or others. Specifically, B.P.D. uses excessive force against (1) individuals who are already restrained and under officers’ control and (2) individuals who are fleeing from officers and are not suspected of serious criminal offenses. Force used on restrained individuals: We found many examples of B.P.D. officers using unreasonable force on individuals who were restrained and no longer posed a threat to officers or the public.

• Cleveland

In May 2015, the Cleveland Police Department agreed to accept close federal oversight of its practices, including how and when its officers were allowed to use force.

The Justice Department found that the Cleveland police routinely used stun guns inappropriately, punched and kicked unarmed people and shot at people who posed no threat. The episodes were often unreported and not investigated, the inquiry found.

A case from 2012, described in the report, illustrates the problem.

An officer’s gun discharged when he struck a suspect in the head with it. The officer, who was off-duty and dressed in civilian clothes, observed what he believed to be a drug transaction take place involving two vehicles and about six suspects. The officer approached them without calling for backup and told them to leave. When “Eric” got out of one of the cars, the officer drew his handgun, pointed it at Eric, and ordered Eric to the ground, identifying himself as a C.D.P. officer but not showing a badge. A witness reported that she saw a man, later identified as the officer, holding a gun to Eric’s face while Eric asked repeatedly for the officer to show his badge and expressed disbelief that he was an officer.

• Ferguson

The Ferguson police used Tasers and dogs in excess on African-American suspects, according to the Justice Department report. In 2013, one black man was chased down and bitten by an officer’s dog even though the officer had frisked him and knew the man was unarmed. The officer’s supervisor later justified the use of force with a patently untrue statement, suggesting that the officer feared “that the subject was armed,” the report said.

• Albuquerque

The police used lethal force in 37 cases s from 2010 to 2014. In them, 23 people were killed and 14 were wounded, an usually high number for a city of about 550,000, the Justice Department report said.

Among the cases cited in that report: Police officers once fired a stun gun at a deranged man who had doused himself in gasoline, setting him ablaze. Another time, they fired one at a man who yelled, “Bang, bang,” as the officers approached. They also fired a stun gun at a 75-year-old homeless man for refusing to leave a bus stop, at a 16-year-old boy for refusing to lie on a floor covered in broken glass and at a young man so drunk he could not get up from a couch.