Canada's police chiefs want legal authority to seize mail in transit to stem the flow of illicit drugs, fake medicine and weapons through the postal system.

In a recently passed resolution, the Canadian Association of Chiefs of Police say contraband is being sent through the mail "with impunity" because the law forbids officers from swooping in until a parcel arrives at its destination.

This poses a "significant challenge" for police, who must find "alternative ways to work within or around" the system to apprehend criminals, the chiefs say.

The resolution calls on the government to amend the legislation governing Canada Post to provide police with the ability to obtain a judge's approval to "seize, detain or retain parcels or letters" in the mail stream.

Canada Post delivered more than nine billion parcels and letters to some 15 million addresses in Canada last year. International mail flows through large plants in the Vancouver, Toronto and Montreal areas.

A November 2012 report prepared by the RCMP for the chiefs' organized crime committee revealed firearms, grenades, a rocket launcher, stun guns, dangerous chemicals and drugs including cocaine, heroin and marijuana were sent through the mail.

"These items represent a significant threat to postal workers and Canadians," say the chiefs, who passed the resolution this month at their annual conference in Quebec City.

"It is imperative that Canada Post and the law enforcement community develop ways to effectively work together to stop the transmittal of contraband through the postal system."

Judicial review adds 'safeguard'

Cara Zwibel of the Canadian Civil Liberties Association said she does not have serious qualms about such a legislative change as long as judicial approval is built into the process.

"I do think it's a really important safeguard," said Zwibel, director of the organization's fundamental freedoms program.

However, she does have questions about the possible criminal consequences for the intended recipient of an intercepted package containing illicit goods — someone "who hasn't yet received it and who actually may not know that it's coming, or may not have asked for it."

The 2012 report noted counterfeit items — from fake Olympic hockey sweaters to bogus passports — were also being shipped into Canada via the post office.

It called for greater collaboration between police and postal officials to detect suspicious parcels.

Privacy remains key concern

However, in a background document accompanying the new resolution, the chiefs say recent court rulings have declared postal inspectors cannot act as agents of the state when tipped by police to contraband making its way through the post.

The chiefs plan to write a letter to the federal public safety minister urging changes to the law, hopefully to be followed up with a meeting.

In addition, members of the chiefs' drug committee plan to discuss the issue with Canada Post representatives in order to further develop the chiefs' strategy for legislative amendments. The chiefs also seek the co-operation of federal, provincial and territorial justice officials.

Zwibel cautioned that any watering down of postal mail privacy could be seen as a precedent to allow easier police access to email.

"We should be careful about eroding the kind of protections that we put around what gets sent through the mail — and what gets sent electronically."