Toronto police have scrapped a plan to acquire a controversial piece of technology that picks up the sound of gunfire and reports it to frontline officers over concerns it could violate Charter rights.

A Toronto police spokesperson confirmed to CBC Toronto that a plan to purchase the ShotSpotter system, touted last summer by Mayor John Tory as a way to help curb gun violence in the city, has been shelved.

While police Chief Mark Saunders was unavailable for an interview Thursday, he said in a statement that concerns about the potential to violate Section 8 of the Charter, which deals with unreasonable search and seizure, as well as the force's research and "the technology that currently exists" led to the decision.

"We have decided to move forward without this technology while still exploring other ways of addressing gun violence and community safety," Saunders said.

Had the preliminary research led the force to move forward, public consultations would have followed, he said.

In response to CBC's questions about advice given to Toronto police about potential Charter violations, a spokesperson for Ontario Attorney General Caroline Mulroney said the Crown would not comment, saying any legal advice they provide is privileged and confidential.

"As technology continues to evolve, the legal issues surrounding the investigation and prosecution of crime will continue to evolve as well," a spokesperson for the attorney general said in an email.

"The ministry is committed to working with law enforcement and other justice system participants to find appropriate ways to address emerging technology and their investigative challenges."

ShotSpotter, which has been used at times by nearly 100 U.S. cities, detects loud sounds, filters them to determine whether they are gunfire and, if they are, forwards a report to police.

Tory was a vocal proponent of the ShotSpotter technology last summer as the city dealt with a spike in gun violence. Toronto also had a record year for homicides in 2018 with 96.

Earlier in the year, Tory announced a $15 million "gun violence reduction plan" that included a larger police presence in what he called "high-priority areas."

Shortly after, Toronto city council voted to approve a five-year $44-million plan that would see investments in enhanced enforcement measures, including the ShotSpotter technology, and community programs aimed at violence prevention.

On Thursday, Tory said early concerns that the ShotSpotter technology might pick up private conversations were initially assuaged by company representatives. However, the "expert advice" police subsequently received created some concern, which led to Police Chief Mark Saunders's decision to shelve the plan.

The gun-violence reduction plan, however, will continue apace, he said. Though a decision on proposals such as increasing the number of closed-circuit police cameras in areas of high gun and gang activity has yet to be made, he told reporters at an unrelated event.

"None of these things were held out as being a magic answer to gun violence in the city," Tory told reporters. "It was one more tool that might have been helpful, and the chief is now of course going to redouble his efforts on all the other fronts so the city can be as safe as it possibly can be."

Coun. Joe Cressy (Ward 10, Spadina-Fort York) says he is 'glad' that Toronto police will not pursue the ShotSpotter technology to tackle gun violence. (Farrah Merali/CBC)

Coun. Joe Cressy, who represents Ward 10, Spadina-Fort York, was a vocal opponent of ShotSpotter when it was first proposed, arguing that it would interfere with residents' privacy. Cracking down on the availability of guns and investing in community programs are the keys to tackling gun violence, he said.

"ShotSpotter did neither of those and so I'm glad to hear that it's not going forward," he told CBC Toronto.

He also accused the city of failing to fulfil promises to residents to deal with gun violence. Council wanted $32 million in funding for community initiatives, he said, but only got $6 million.

"We need to get rid of the scourge of gun violence that is killing youth throughout this city…and we know how to tackle gun violence. You ban handguns and you invest in strong and safe communities," Cressy said.

"You cannot arrest your way to a solution on its own, nor can you put up enough audio cameras and recording devices to stop it."

Mike McCormack, president of the Toronto Police Association, said community policing will be key to curbing gun violence, but that requires more officers on the ground. He said a pledge to hire some 300 officers, 250 civilians and more than 100 special constables is "a step in the right direction."

But "we aren't surprised" ShotSpotter has been scrapped, he said, given the concerns over privacy and what he characterized as mixed results in some U.S. cities that deployed the technology.

"People are looking for a panacea or a quick fix to the gun violence," he told CBC. "As we've said for a long time, there is no quick fix."