News and videos of police killings of unarmed blacks across the country have enraged African Americans and fed a growing anti-police abuse movement over the last year. But many elected officials and top cops in Boston continue to stress that Boston is different.

Their claim of the city’s exceptionalism was recently challenged.

Last week, the ACLU of Massachusetts announced a lawsuit against the MBTA Police Department for police brutality and posted its webpage video recordings of the 2014 incident. Boston residents gained access to disturbing footage of the type of abuse many in the black community have complained about for decades.

The video came not from body-worn or dashboard-mounted cameras, but from an array of video recorders mounted in the Dudley Station bus terminal. The video’s release underscored how effective recorded evidence can be at changing the narrative in police abuse cases.

In March of last year, following her arrest by MBTA Police officers Jennifer Garvey and Alfred Trinh, Mary Holmes was facing charges of assault and battery on a public employee, resisting arrest and disorderly conduct. Like many in the black community who have experienced police abuse, Holmes might well have faced the daunting choice of either pleading to reduced charges or rolling the dice with the often majority-white Suffolk County juries that all-too-often side with the police.

“She could be in jail or on probation if it weren’t for the video,” said ACLU Massachusetts Attorney Carlton Williams, who defended Holmes in court.

Instead, the taped images Williams turned up showed clearly that Holmes did nothing to warrant an attack.

“What amazes me is that Ms. Holmes has her hands in her pockets,” says Howard Friedman, who is representing Holmes, along with the ACLU, in a civil case against the MBTA. “It’s almost what you’d be trained to do if you don’t want to get charged with assaulting an officer.”

The video evidence prompted the Suffolk County District Attorney’s office to file a “nolle prosequi,” stating that it was “in the best interests of justice” not to prosecute the case. Last week, Holmes filed a civil suit against the MBTA charging civil rights violations.

Confrontation in Dudley Station

Holmes initially approached Garvey when she saw the officers scream at and shove an elderly black woman. While Holmes was calling 911, Garvey advanced on her. As Holmes backed away, Garvey sprayed her in the eyes with pepper spray, then beat her with a metal baton and, along with Trinh, forced Holmes to the ground.

The incident was captured on four surveillance cameras installed in the Dudley Station bus terminal.

The charges leveled against Holmes — assaulting a public employee, disorderly conduct and resisting arrest — are not uncommon in cases where officers beat a civilian, and don’t necessarily mean the accused have broken any laws.

“Police use them as subjective crimes,” Williams said. “They mean ‘you’re doing something I don’t like. I’m going to arrest you.’ [Holmes] was a black woman who stood up. She was beaten for it.”

As happens increasingly in incidents around the country, the video evidence presented a radically different truth than those outlined in the charges the officers heaped on Holmes, effectively shifting her legal status from villain to victim.

“Video evidence is coming up in more and more cases,” Friedman said. “Sometimes it’s a hand-held video recording. Sometimes it’s a security video. More and more, they’re contradicting what’s in the officer’s report.”

Growing body of evidence

Nationally, the proliferation of cellphone videos over the last year has helped fuel protests and calls for criminal justice reform, including a reform package that members of the Massachusetts Legislative Black and Latino Caucus are backing on Beacon Hill.

So far, the impetus for reform is spurred by events in other cities — the chokehold killing of Eric Garner at the hands of New York Police Department officers in Staten Island, the cold-blooded police shooting in Cleveland of 12-year-old Tamir Rice, the senseless shooting death of Cincinnati resident Samuel DuBose, captured on the body-worn camera worn by a University of Cincinnati police officer.

Calls for reform have landed on the desks of Boston’s 13 city councilors, who in August held a hearing on a proposed ordinance that would require police to be outfitted with body-worn cameras. During that hearing, councilors praised the Boston Police Department for building trust with Boston residents. But Councilor Tito Jackson, one of two councilors who expressed explicit support for the measure, warned Police Commissioner William Evans that trust is fragile.

“The toughest thing about the power of trust is that it’s very difficult to build and very easy to destroy,” he said. “Every city in the country is one incident away.”

A history of police abuse

The Holmes case is by no means the first time MBTA officers have been accused of excessive force.

Beginning in the late ’90s the MBTA Police came under fire for a series of allegations of excessive force. In a 1999 incident, MBTA cops used batons and dogs to arrest nine commuters in Dudley Station after an officer used pepper spray on a woman accused of fare evasion. In the face of overwhelming eyewitness accounts, prosecutors dropped the charges against all nine. Former MBTA Police Chief Thomas O’Loughlin eventually resigned and the agency disbanded controversial units that were responsible for large numbers of complaints.

Boston Police also sparked controversy in recent years. In a series of officer-involved shootings in the early 2000s, police killed eight civilians in one 22-month period, including four incidents in which drivers or passengers in cars were gunned down. In one incident, Eveline Barros Cepeda, a 22-year-old mother, was killed by a bullet fired through the back of her car as it was driving away from a police officer.

While eyewitness accounts contradicted police reports in several of those cases, no officers were charged in those shootings or any others in recent Boston history.

“I think that if the police had body cameras, there would have been different outcomes to those situations,” says former City Councilor Chuck Turner, who convened a hearing on the spate of police shootings in 2002. “Right now there is still nothing to protect residents from police exercising their desire to exert power and control without regard to the legality involved in a situation.”

In Holmes’ case, the public release of the video evidence appears to have spurred MBTA police to take a fresh look at the case. Although Garvey was initially cleared of any wrongdoing in the incident, an MBTA spokesman told the Boston Globe the agency is bringing in an outside investigator to look at the case.

Whether or not the police adopt body-worn cameras, it seems likely that video evidence will level the scales of justice that for decades have been tilted toward the police. As cell phone videos and video feeds from the city’s ubiquitous security cameras become more frequent, plaintiffs in police abuse cases may also see a substantial reduction in the amount of time they spend in litigation, according to Friedman, whose law practice handles civil rights and police abuse cases.

“They’ll want to settle these cases quickly because they’re going to lose,” he said. “They don’t want to spend their time defending a case they’re not going to win.”

“Let’s hope it changes police officers’ behavior,” he added.

The missing dashboard cameras

Meanwhile, the Boston police continue to grapple with the integration of technology and law enforcement.

While Boston Police Commissioner William Evans and a majority of Boston’s City Councilors have expressed deep reservations about body-worn cameras, the city did for a while have dashboard cameras mounted on traffic enforcement vehicles.

Evans made that revelation during his testimony at the City Council hearing on body-worn cameras earlier this month.

“We had them at one time on our traffic vehicles,” Evans said, in response to a question from Councilor Josh Zakim. “Again, that’s something we’re looking at.”

“Was that a cost issue or…?” Zakim asked.

“You know we just got a whole new fleet of vehicles, and we had them on a fleet of vehicles, but again, with the study, we’re going to look at those dashboards, as well as the body cameras.”

The Boston Police Department’s Media Relations Department did not answer questions, by phone and email, about when, why or how many cameras were removed.