When public officials refuse to release a video that shows alleged misconduct by a police officer, you should only expect the worst.

That’s particularly true in Chicago, where one “bad apple” too often has signaled a bushel of coverups and other problems underneath.

Such are the suspicions that haunt the city’s stalling for more than a year to release a dashcam video that shows former Officer Jason Van Dyke firing 16 shots into the body of 17-year-old Laquan McDonald, an African-American.

Mayor Rahm Emanuel denounced the behavior as a case of one allegedly bad apple. Yet the video and various actions taken before and after the shooting point to systemic and institutional problems that extend far beyond one allegedly trigger-happy cop.

Why, for example, did the city sit on the dashcam video for more than a year before a judge ordered its release on open-records grounds?

Mayor Emanuel and Cook County State’s Attorney Anita Alvarez have said the time was needed to conduct proper investigations. But compare that to the Cincinnati case last summer in which black driver Samuel DuBose was fatally shot on camera by University of Cincinnati police officer Ray Tensing during a routine traffic stop.

The video, which contradicted Mr. Tensing’s account of being dragged by Mr. DuBose’s vehicle, was released and Mr. Tensing was charged with murder and fired from the department in less than two weeks.

The Chicago video similarly refutes a police union spokesman’s allegation of Mr. McDonald lunging at police with a knife on the night of Oct. 20, 2014.

Instead it shows the teen, reportedly with PCP in his system, holding a small knife but moving away from police when Mr. Van Dyke opens fire — and inexplicably keeps firing at Mr. McDonald’s flinching body on the ground. Only Mr. Van Dyke fires his weapon and none of the estimated seven police officers on the scene moves to help Mr. McDonald. Mr. Van Dyke has been charged with first degree murder.

Then there’s the question of what happened to video from a security camera at a nearby Burger King. A district manager for the restaurant chain has said police visited shortly after the shooting and were given access to the surveillance equipment. The next day, he has said, a portion of the video was missing.

Witnesses to the shooting told Jamie Kalven, an independent journalist and human rights activist whose nonprofit called the Invisible Institute filed a FOIA request to have the dashcam video released, that police tried to shoo witnesses away from the scene after the shooting instead of collecting names and other information.

And why, many wonder, did the mayor persuade the City Council to authorize a $5 million settlement for Mr. McDonald’s family, which had not filed a lawsuit. Mayor Emanuel claimed a desire to avoid jeopardizing the case. But Chicagoans with long memories — like me — wonder whether the cash is reparations or a form of hush money.

The city fought to conceal the video, even after the Wall Street Journal, the Chicago Tribune and a freelance journalist all filed FOIA requests for its release.

To Mr. Kalven, the most important issue here is not just the shooting but how governmental institutions — from the police to the mayor’s office — responded to it, he says.

“And at every level,” he told me in a telephone interview, “we can see they responded by circling the wagons and creating a narrative that they knew was completely false.”

Mr. Kalven’s institute worked seven years to open up police files and establish an online database of misconduct complaints against police officers — 97 percent of which resulted in absolutely no disciplinary action.

Among other issues, Chicago and other cities will have to determine, like the rest of us, how to adjust to the new video age, an age that exposes so much to public view that used to be swept under various rugs.

The McDonald video reveals the flip side of the so-called “Ferguson effect,” a widely alleged tendency by some police to hesitate before responding to crime scenes for fear of getting caught in a career-ending cellphone video. If fear of video can prevent atrocities like that revealed in the McDonald case, that’s not a bad thing.