Experts say they're baffled by the big drop in the number of applications from police to conduct electronic surveillance on citizens.

In 2015, peace officers asked for authorization to intercept and record private communications 66 times, down from 114 a year earlier.

Police can ask a judge for permission to intercept someone's personal communications when they suspect serious criminal activity. Such authorizations generally last around 60 days.

The data comes from the Department of Public Safety's annual report on the use of electronic surveillance in Canada. 

The report describes how, when applying for authorization, police most often said they suspected drug trafficking, terrorism, conspiracy and possession of stolen property. It also says charges were laid against 56 people identified during an interception.

Brenda McPhail welcomes the information, but the director of privacy, technology and surveillance for the Canadian Civil Liberties Association, can't explain the drop. McPhail says there's a limit to how helpful numbers are without any analysis.

"We could wonder whether or not the categories they are required to report in are so narrow that they are not catching the new kinds of interception technologies and techniques that are being used," she said.

Christopher Parson agrees. He's with the telecom transparency project at the Munk School of Global Affairs' Citizen Lab.

"Wiretaps are meant to be a tool of last resort so what that may suggest is authorities are finding other ways of gaining evidence that is less intrusive on Canadians' privacy, more generally," Parsons told CBC News.

Parliamentary security committee coming

That has the potential to be a good thing, according to Parsons.

"Unfortunately we don't have data on any of the other tools law enforcement uses. One of the anomalies in the Canadian situation, actually, is outside of these reports, we really have no clear indication of how often police are using their powers," said Parsons.

The government is currently holding consultations on Canada's national security framework. A spokesman for the Department of Public Safety says the public should share their views about police and security agency investigative capabilities in a digital world. 

"More broadly, the government is advancing legislation to establish a committee of parliamentarians with special access to classified information to increase the accountability of all security agencies and departments," added spokesman Scott Bardsley.