Follow CBSDFW.COM: Facebook | Twitter

BOSTON (CBSDFW.COM/AP)After years of testing in North Texas and across the country, many of the nation’s big-city police forces are planning to expand their use of body cameras, but the number of officers with such gear will still be relatively small, an Associated Press review found.

The 2014 killing of Michael Brown in Ferguson, Missouri, and other deaths at the hands of police around the U.S. have led to demands that officers be issued wearable cameras to deter misconduct and document shootings and other clashes. But because of cost concerns, union resistance and other factors, the rollout has been slower than some cities envisioned.

An AP look at the nation’s 20 largest local departments found that Chicago has begun issuing the devices to over 2,000 officers, or less than 17 percent of its roughly 12,000-member force, though it says it will eventually offer them across the department. Philadelphia has begun equipping about 5 percent of its force and Houston nearly 6 percent.

It was late last year when dozens of officers with the Dallas Police Department were equipped with body cameras. The push for body cams in the city came after the police shooting of a mentally challenged man was caught on camera. One DPD officer was fired and another charged after lying about why the officer shot the man, who was standing with his arms at his side. It was the neighbor’s surveillance camera that captured the truth.

New York, the nation’s largest city police force, says it plans to purchase 1,000 cameras by the summer, or enough to outfit less than 3 percent of its 34,000-plus officers. But the department said Tuesday there is no date for when those will be put to use, and no plan as yet to equip more officers.

For some cities, the expansion comes in anticipation of the summer, when crime typically rises. For others, the availability of federal money to help pay for the technology is a driving factor.

Some suggest that in many cities, the number of devices in use is far smaller than what politicians and law enforcement leaders had been promising over the past year and a half.

“I would suspect we’re woefully short,” said James Pasco, executive director of the National Fraternal Order of Police. “They make these lofty pronouncements and then they don’t put their money where their mouth is.”

Darrel Stephens, executive director of the Major Cities Chiefs Association, said cities are moving fairly swiftly, considering the complex questions at stake.

“I am not necessarily troubled by the pace,” he said. “This is a major technological investment. It is reasonable for police to go slow.”

Police have warned that processing, reviewing and storing huge amounts of digital footage will require more manpower and entail significant costs.

In Los Angeles, the City Council balked at an ambitious plan to outfit about 7,000 officers with body cameras by the end of this year, amid concerns over its projected $58 million cost over five years. The department, which rolled out 860 cameras last year, now hopes to meet its goal by the fall of 2017, at the earliest.

Other departments are pushing forward.

Baltimore, which erupted in riots last year following the death of Freddie Gray from a spinal injury suffered in police custody, expects to have 500 officers using them by this month, or about 17 percent of its force. It hopes to have most officers equipped with them by early 2018.

Boston’s roughly 2,100-member police force promises to launch a six-month test of 100 cameras by July. Some residents say the rollout is long overdue.

“At some point, Boston could have a Ferguson,” Rachel Idowu said. “Let’s put the cameras on to prevent that from happening. Rather than be reactive, let’s be proactive.”

But others have balked at the projected cost of $3 million to $5 million to expand it department-wide.

“We need to be judicious,” said Juan Seoane, a Boston detective and resident. “You’re going to have to raise taxes, or you’re going to have to take things away from the community.”

Civil rights groups say they are less concerned about the pace of adoption than about how the police intend to use the cameras. Many policies don’t adequately address privacy and civil rights concerns, such as when officers should activate the cameras, how long video should be stored and when the public can see it, they say.

In Los Angeles, for example, the American Civil Liberties Union and others last month came out against the department’s body-camera guidelines because, among other things, they say the release of footage to the public is up to the police chief, unless ordered by the courts.

“The jury’s still out on whether cameras are a useful tool in reducing excessive force in policing,” said Sakira Cook, legal counsel for the Leadership Conference on Civil and Human Rights, a Washington-based coalition. “We’re also concerned cameras can be used as tools of surveillance and increase racial profiling.”

(©2016 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)