INSTANCES OF people illegally imprisoned — without legitimate cause and denied the chance to see a judge or lawyer — may be commonplace in dictatorships and third-world countries, but they really shouldn't occur in the United States. Better tell that to the officials who run the D.C. jail, where a 28-year-old man languished for more than two months because someone made a mistake.

The alarming case of Carlton O. Harris was detailed by The Post's Spencer S. Hsu in an account that should have the mayor and D.C. Council demanding answers. According to the report, Mr. Harris was mistakenly held at the jail for 77 days even though the misdemeanor charge that resulted in his arrest March 28 was dropped the next day. Only when another inmate at the jail told his attorney about the situation did officials realize there was a problem. Mr. Harris was eventually released June 15.

The D.C. Department of Corrections flatly refused comment, citing "safety and security reasons," but The Post quotes an unnamed law enforcement official faulting "a clerical error by the D.C. Department of Corrections." Remarkably, Mr. Harris's case doesn't appear to be isolated: The department has been subject to other complaints about overdetention and had to pay $6 million in a 2013 settlement of a federal court action. A new class- ­action lawsuit alleges that the extent of the problem is being hidden.

D.C. Council member Charles Allen (D-Ward 6), chairman of the judiciary committee, called the Harris case "pretty egregious" and told us he has asked for information from the corrections department and the U.S. Marshals Service, which transports prisoners and was rebuffed when it sought Mr. Harris's transfer on a warrant for a 2013 Maryland traffic violation. It is important that any review include not only how the initial mistake occurred but also why Mr. Harris was apparently too afraid to raise the issue even as the days turned into weeks and he lost his job and faced other hardships.

Other inmates told him he was not supposed to be jailed for more than a couple of days without seeing a judge, but he thought he would be ignored or punished if he complained. "You speak up, they can go real bad," he told The Post. District officials owe it to Mr. Harris to figure out what happened and, for the sake of others in their custody, put changes in place to prevent future mistakes.