When the shooting stopped that night in November 2012, a man and a woman, both African-American, were dead, riddled with bullets in the car’s front seat. There was no evidence that either had a gun. Investigations suggested that they had set out to purchase crack cocaine in a car that apparently backfired as it passed an officer, and then panicked when the police tried to pull them over.
Late last month, one officer was indicted on manslaughter charges and five supervisors were charged with criminal dereliction of duty.
The Department of Justice has also opened a wide-ranging civil rights investigation that could lead to years of court oversight and mandated controls on the use of force.
It is the latest in a series of sharp federal interventions in police departments across the country, part of an initiative that Attorney General Eric H. Holder Jr. considers a signature achievement, forcing change and accountability on insular police departments.
“For me, it’s kind of personal,” Mr. Holder said in an interview. In his days as a prosecutor and a judge in Washington, D.C., he recalled, strong criminal cases had crumbled because jurors mistrusted the police.
“Sometimes people think a choice has to be made between lawful, respectful policing and effective policing,” Mr. Holder said. “I think they are mutually dependent.”
The federal investigations are often followed by agreements called consent decrees and years of court monitoring. Even cities that have not come under direct scrutiny have been encouraged to tighten rules for using Tasers and guns, to find better ways to deal with mentally ill suspects and to adopt new technology such as on-officer video cameras.
Some police departments and political leaders have pushed back. Last month, more than 100 officers in Seattle filed a suit to block a court-ordered plan there, saying it imposed unrealistic limits that put police and the public at risk. Some experts have criticized the interventions as overly intrusive and costly.
