The Liberal government has been expanding the number of public servants subject to lifetime gag orders, placing them under threat of hefty prison sentences should they spill any secrets before they die.

Since December, the Privy Council Office has designated at least 94 individuals, some of whom no longer work for the federal government, as "persons permanently bound to secrecy" or PPBS — a binding legal order intended to enforce their silence.

The group all had access to confidential, security-related information while working at the Privy Council Office or the Prime Minister's Office, and some were served with official notice of the gag order after they had left their jobs.

Each of them was individually identified by their boss or former boss as knowing secrets about national security, and therefore requiring a gag order that is retroactive — preventing them from talking about their work before the gag order was issued.

Each was also presented with a three-page notice to sign and return, many using a pre-paid, pre-addressed envelope that was enclosed.

CBC News learned about the latest round of lifetime gag orders through a request under the Access to Information Act, and some details have been confirmed by a government spokesperson.

Gagged for life

A heavily redacted memorandum for the clerk of the Privy Council dated Dec. 19, 2016, also shows another 145 Privy Council Office staffers have been subject to blanket gag orders under the Security of Information Act since 2014 because of the nature of their roles.

These individuals were automatically gagged for life because they work in units that are designated as sensitive and are routinely exposed to secrets, unlike the 94 who were selectively added to the gag list because they are only sometimes given secret information.

The Privy Council Office declined to provide more information about the 94, including how many may have worked in former prime minister Stephen Harper's office.

"Further disclosure of information could lead to security risks, potentially placing Canadians at risk," spokesperson Paul Duchesne said in an email.

The briefing note for the clerk indicates the Privy Council Office expects to add about 30 individuals each year to the ranks of "persons permanently bound to secrecy."

A separate group of more than 200 Canadian military personnel and federal workers have also been hit with lifetime gag orders since early last year. These individuals all work in the controversial program to replace Canada's fighter jets.

After a formal question submitted in the House of Commons by Conservative MP James Bezan, the government acknowledged more than 200 public servants have been gagged for life regarding their work in procuring new fighter jets. (Adrian Wyld/Canadian Press)

The number was elicited by Conservative defence critic James Bezan through a formal House of Commons procedure that requires a minister to answer an MP's question. Insiders called the gag orders an extraordinary and unnecessary measure.

Of the 235 staffers disclosed to Bezan, 121 work for National Defence and 13 work for the Privy Council Office. It's not clear whether any of the 13 at Privy Council are also counted in the clerk's memo.

Myth of the 'eternal secret'

In total, these most recent reports add at least another 361 public servants who risk up to 14 years in prison if they ever discuss the secrets of their time in government, whether in memoirs or at family reunions.

Security and intelligence historian Wesley Wark says the gagging system under the Security of Information Act of 2001 is unworkable and poorly conceived.

It "rests on an idea that there is such a thing as a permanent or eternal secret," the University of Ottawa professor said. "This is clearly a myth and an unhelpful one."

Wesley Wark, a security and intelligence historian at the University of Ottawa, says the gag provisions of the Security of Information Act are outdated and rob Canadians of their history.

He says the concept "robs Canada of an ability to learn from the experience of officials with a deep knowledge of security and intelligence issues" and "creates a chill around the publication of memoirs and other forms of organized memory and commentary."

"It is a very old-fashioned system, rooted in long-ago British practice and has not been updated."

Wark says the law needs to be rewritten to ensure the gag provisions apply only to select categories of highly sensitive intelligence, among other reforms.

But Duchesne of the PCO says there are no plans to change the system.

"Designation of PMO and PCO employees will continue, as required in the interests of security," he said. "Both PCO and PMO take the protection of information very seriously, which is why both ensure that those who have access to special operational information are permanently bound to secrecy."

On May 11, historians and their supporters launched a petition to the federal government, calling for millions of documents that have spent decades in departmental filing cabinets to be turned over to Library and Archives Canada.

The petition's initiator, Dennis Molinaro of Trent University, told CBC News "the government seems to be, in essence, running some kind of secret or shadow archive."

Follow @DeanBeeby on Twitter