IN 2013, a man contacted the Baltimore police with a complaint. As described by a recent Justice Department report, he said he had been hospitalized after two officers slammed him to the ground during an unjustified arrest. What happened next was a travesty of justice by any normal standards but par for the course for Baltimore’s police department.

The case went uninvestigated for 13 months, shuttled between two commands and buried in the bureaucratic folds. An internal audit flagged it, at which point it languished four more months before being assigned to an internal affairs detective. Finally, the case was dismissed for “lack of cooperation” when witnesses failed to appear — 17 months after the incident. Incredibly, the accused officers were never interviewed.

Impunity is so deeply ingrained in Baltimore’s police culture that this incident barely raises a ripple in the riptide of institutional arrogance, unaccountability and corruption. Elsewhere in the Justice Department’s report, one finds accounts that complaints of abuse and excessive force are shunted into oblivion for lack of a notarized form; of cases dismissed because the allotted time to investigate has “expired”; of a supervisor who refused to accept a complaint because she “could not go against” her own officers. In many cases, the police just couldn’t be bothered.

Investigations, when they take place at all, are cursory; record-keeping ranges from shoddy to nonexistent. Of 1,382 allegations of excessive force between 2010 and 2015, the police deemed just over 2 percent worthy of disciplinary hearings; complaints of rude and abusive conduct by officers were also routinely ignored, despite abundant evidence that discourtesy is rife.

Underlying the culture of impunity is a matrix of laws, rules and procedures that rig the system so thoroughly that discipline is rare, often reserved for cases that make a stink in the media. Under a state law known as the Law Enforcement Officers’ Bill of Rights, three-member trial boards pass judgment in cases of alleged serious misconduct. But the accused officers themselves are entitled to veto any or all members of a board, which to begin with includes a fellow officer of their own rank and no civilians. Officers are thus nearly assured friendly trial boards — no wonder discipline is so seldom imposed.

When complaints are received by the police, justice is further impeded by endless and apparently intentional delays in investigations, coupled with willful misclassification of the nature of the misconduct. Complainants are required to submit their reports on notarized forms at a limited number of offices; complaints made by email and phone are disqualified.

Officers accused of misconduct are immediately given a detailed account of the complaint, despite an auditor’s warnings that doing so may subject complainants to intimidation and retaliation. Accused officers are also afforded privileges no civilian enjoys — for instance, to review evidence and documents before they are questioned. The entire process is hidden from public view, making it even more susceptible to abuse.

The department’s abysmal record of harassing people in the communities it is sworn to protect has been well-documented. What remains to be seen is who will police Baltimore’s police when state and local authorities have already failed so spectacularly to do so.