Baltimore Police Commissioner Kevin Davis delivers a statement Aug. 10 during a news conference in response to a scathing Justice Department report about the city’s police department. (Kim Hairston/The Baltimore Sun via Associated Press)

IN THE Justice Department’s damning, astonishing report on the ingrained, systemic racism in Baltimore’s police department, one tidbit captures the larger picture. It describes an email by a city police supervisor containing a template for officers making trespassing arrests, with blanks to be filled in for date, location, suspect’s name and address — yet, oddly, no prompt for race or gender. Instead, the words “black male” were automatically included.

That must have been a convenience for Baltimore patrol officers, who, as the report details, have routinely used minor charges to harass, detain and arrest African Americans for the offenses of walking down the sidewalk, gathering on a corner and speaking to police the wrong way.

If that assertion prompts a raised eyebrow, consider this: In the five-year period ending last summer, blacks — who comprise 63 percent of Baltimore’s population — accounted for roughly 90 percent of suspects charged with trespassing, failing to obey an officer’s orders or “impeding” an officer. Eighty-four percent of those charged with disorderly conduct were black. And in a disproportionate number of those relatively trivial cases, where the arrests depended on an officer’s discretion, the charges were ultimately dropped.

What is clear in the report is that as a matter of culture and practice, Baltimore has long had two enforcement regimes: one for African Americans, which is often unlawful and unconstitutional, and another for everyone else. This explains why Freddie Gray was arrested in April 2015, and why he ran when a patrol car came into view.

In a news conference unveiling the report Wednesday, Vanita Gupta, who leads the Justice Department’s Civil Rights Division, Baltimore Mayor Stephanie Rawlings-Blake (D) and Police Commissioner Kevin Davis spoke about the cooperation they have undertaken and expect as they negotiate a court-enforceable decree imposing sweeping reforms on Baltimore’s police. At the same time, they noted that the reforms will be slow and difficult — an epic understatement.

The problem is not a few bad apples, as Mr. Davis suggested in saying the abuses were carried out by “a relatively small number of police officers.” To the contrary: The problems are cultural, institutional and legal. Real change will encounter massive resistance, especially from the union representing police, which beat back legislation in Annapolis this year that would have required disciplinary trial boards in cases of serious police misconduct to include civilians, not just officers. Instead, lawmakers, quailing at the union’s opposition, decided only that civilians may be included on the boards — which, in practice, is unlikely to happen.

The fact that trial boards are required before police face serious discipline arises from state legislation, the Law Enforcement Officers’ Bill of Rights, which provides officers accused of wrongdoing with a matrix of protections — and impediments to discipline — unavailable to other public employees (except prison guards) or to police in most other states.

Mr. Davis, who took office after Gray’s death, has pushed some reforms, including a more rigorous use-of-force policy. Yet his recent ruling that officers under investigation could view police footage of the incident in question before being questioned — a privilege unavailable to other subjects of investigations — cast doubt on whether he and other community leaders have the spine to effect a culture shift that includes real accountability.