BALTIMORE — Baltimore police officers routinely discriminate against blacks, repeatedly use excessive force and are not adequately held accountable for misconduct, according to a harshly critical Justice Department report being presented today.

The report, the culmination of a yearlong investigation into one of the country’s largest police forces, found that officers make large numbers of stops — mostly in poor, black neighborhoods — with dubious justification and unlawfully arrest citizens for disrespectful speech. Physical force is used unnecessarily, including against the mentally disabled, and black pedestrians and drivers are disproportionately searched during stops, the report says.

The Justice Department released a copy of the report in advance of its public announcement at an event today in Baltimore.

The report represents a damning indictment of how the city’s police officers carry out the most fundamental of policing practices, including traffic stops and searches and responding to First Amendment expression. Beyond that, though, it could serve as a blueprint for sweeping changes: The Justice Department is seeking a court-enforceable consent decree to force the police agency to commit to improving its procedures in order to avoid a lawsuit.

The Justice Department recently has undertaken similar wide-reaching investigations into the police in Chicago, Cleveland, Albuquerque and Ferguson, Mo., among other cities.

The federal investigation was launched after the April 2015 death of Freddie Gray, a 25-year-old black man whose neck was broken while he was handcuffed and shackled but left unrestrained in the back of a police van. The death set off protests and the worst riots in decades.

The report went far beyond the circumstances of Gray’s death to examine a slew of potentially unconstitutional practices, including excessive force and discriminatory traffic stops, within the department.

Federal investigators spent more than a year interviewing Baltimore residents, police officers, prosecutors, public defenders and elected officials, as well as riding along with officers on duty and reviewing documents and complaints.