When Somerville Mayor Joe Curtatone declared that systemic racism constitutes a public safety and health emergency last week, he called for several new reforms. But he also reiterated his call for a policy he’s been trying to implement for years: body cameras for Somerville police officers.

"We have been attempting to negotiate with the unions and implement body cameras across the force for the last five years," Curtatone said. "I’d describe it as frustrating."

To date, Curtatone says, he hasn’t been able to convince union leadership that cameras are good not just for community relations, but also for the police.

"The utilization of body cameras brings another level of transparency that the public deserves and needs," he argues. "And at the same time, it would help keep police officers safe and protect them from liability. There’s no lying in front of the camera. We know what happens."

Right now, no Somerville police officer wears a camera. Curtatone’s goal is a system in which all officers wear them — and don't have the latitude to disable them.

"That must be mandated in all situations," Curtatone said. "Officers cannot have the discretion to turn them off."

That’s not how it currently works in Boston, where Mayor Marty Walsh had to go to court to launch a body-camera pilot program back in 2016. When the city launched a pilot program that year, Walsh told WGBH News that full implementation would be expensive, but might be worth it.

"Building trust in the community is by getting out of the car and talking to the police," Walsh said. "Body cameras, you have information on film if something is going happen."

Much has changed in four years. A BPD spokesperson says that of 1100 patrol officers on active duty, only 30 don’t have their own camera and the training to use it.

Still, Boston gives officers wide discretion when it comes to turning the cameras off. According to the BPD's official body-camera policy, acceptable reasons include “the sensitive or private nature of the activities or circumstances observed,” "the presence of individuals who are not the subject of the officer-civilian interaction,” and "the extent to which absence of...recording will affect the investigation."

In addition, Boston doesn't require officers to wear body cameras when they're working overtime. During recent protests in the city, that policy meant that a majority of officers on duty were camera free.

Given all this, Boston City Councilor Andrea Campbell contends, it's time for a public, wide-ranging discussion of how the city's body-camera program is working and how it could be improved.

"We need updates," Campbell said. "We need to close any potential loopholes in the policy, and we need to get this right. I’m hoping this climate and this context will create a greater sense of urgency."

A mayoral spokesman says Walsh is ”fully supportive of body cameras being worn by officers during all shifts, including overtime." The spokesperson also says Boston Police “are actively working toward that goal.”

There's a paradox at play here, however. As calls grow to “defund the police," proposals to spend new or additional money on body cameras might not get the support they used to from advocates.

Case in point: Segun Idowu, the co-founder of the Boston Police Camera Action Team, which pushed the city to implement cameras a few years ago.

"We're actually not pushing for the adoption of more body cams, but are instead joining other advocates and organizers on the ground to just completely overhaul the budget of the police department and reduce the amount of money we’re giving to them," Idowu said.

"If there's a way for us to rejigger the police budget, and move money around, I think we'd be for that," he added. "But in terms of adding more money to the police budget, that's not something that we're for."

That shift comes, ironically, as some police may be starting to view cameras as a tool to be embraced rather than rejected.

Springfield, Mass. is rolling out body cameras right now, and plans to have every officer equipped by the end of the year. When the contract containing that provision was finalized, Joe Gentile, the head of the Springfield patromen’s union, described the shift that led his members to support it.

“There is a fear of the unknown, and we have a little of that," Gentile said.

"We worked really hard on the policy, and the city was reasonable in working with us on the policy," he added. "And for that reason, we feel we'll be able to lead the way."