The Hamilton Police Service is refusing to say whether it's using technology that acts like a cell tower to secretly intercept and track cell phone calls and data in a particular radius.

Hamilton is the latest of several Canadian police forces that refuse to confirm or deny whether the service uses the covert surveillance technology.

Any police force could use this for a variety of reasons that would or would not be warranted, and we wouldn't know. - Ann Cavoukian, executive director of the Privacy and Big Data Institute at Ryerson University

But recent court cases and media investigations have revealed some law enforcement agencies like the RCMP use it to target and intercept Canadians' mobile phones in major crime investigations across the country.

The technology is known as a cell-site simulator, better known by brand names like Stingray. While its use is more widely known in the United States, it's been very recent that court cases have revealed that RCMP officers have been using the technology in Canada.

Its use became the focus of a federal privacy commissioner's investigation launched this spring.

Civil rights groups across the country have raised concerns about the devices, which, depending on the model, enable officers to secretly monitor phone calls and anything transmitted from mobile phones, like text messages, photos and location information. Some gather information from the phones of bystanders nearby.

'We wouldn't know'

Typically law enforcement must obtain a warrant to search someone's house or person, and the advocates want to see that legal oversight applied with the new technology.

"Without the necessary court authorization, I object to the use of this across the board," said Ann Cavoukian, the executive director of the Privacy and Big Data Institute at Ryerson University.

"Any police force could use this for a variety of reasons that would or would not be warranted, and we wouldn't know," she said.

That potential for blanket surveillance without public accountability cause concern for civil rights advocates.

'Failure to acknowledge if and when'

The RCMP testified during a Montreal-area murder case that they are using cellphone surveillance technology in various ongoing investigations across Canada, including probes of murders, organized crime and drugs. (Chris Young/Canadian Press) Hamilton Police denied a request by CBC Hamilton under the Municipal Freedom of Information and Protection of Privacy Act to see any records relating to the service's acquisition and/or use of the Stingray-type technology.

The service refused "to confirm or deny the existence of a record," citing the possibility that disclosure could either reveal investigative techniques used or possibly being used by police.

CBC Hamilton has filed an appeal of that denial to the provincial Information and Privacy Commissioner.

Hamilton Police did not respond to a request for an interview about under what circumstances Hamilton Police uses a cell-site simulator, such as a Stingray, and if it has its own such device or whether it borrows from the RCMP.

Cavoukian said learning about the technology's use after the fact, in court, doesn't help the public trust police.

"Learning about these things indirectly adds to the distrust on the part of the public," she said.

Clint Twolan, who represents officers as head of the Hamilton Police Association said users of smart phones already share information about their whereabouts with the corporations whose services they use, like Google and Apple.

"I trust police more than I trust Apple," Twolan said.

'We have to be so careful about the expansion of surveillance'

Hamilton Police denied a request by CBC Hamilton under the Municipal Freedom of Information and Protection of Privacy Act to see any records relating to the service’s acquisition and/or use of the Stingray-type technology. (Dave Beatty) But Cavoukian said she might feel differently "if there was some openness and transparency, if police said, 'Look, we've got to catch these bad guys – here's our best chance of doing it."

"The society that we're evolving into, as these technologies become better and better and less transparent, we have to be so careful about the expansion of surveillance and how it impacts our freedoms," Cavoukian said.

The refusal to disclose even the existence of the technology is problematic for a Vancouver-based group called OpenMedia that complained to the federal privacy commissioner.

The Canadian Civil Liberties Association calls for:

Requiring police having to obtain a warrant in order to use the device, including disclosing any risks of their use.

Instituting appropriate safeguards that are made public so the public can evaluate them.

Mandating that devices may only be used "in compliance with the principles of necessity of proportionality as part of a targeted investigation".

Requiring police delete the information that was collected from bystander.

In the United States, the American Civil Liberties Union has confirmed dozens of local and federal forces using the technology, and has called for government disclosure of when and where the devices are used.

For U.S. federal law enforcement, the Department of Justice last fall announced it would require officers to obtain a search warrant before using the technology.

kelly.bennett@cbc.ca | @kellyrbennett