Canadian federal scientists need to have more freedom from political influence, their advocates say, as the union representing government researchers heads to the bargaining table this week.

The federal government has been accused of muzzling its scientists, denying them the opportunity to speak to the media, express their opinions or present their work at scientific conferences.

The Professional Institute of the Public Service of Canada says it will push to have "scientific integrity" enshrined in its next collective bargaining agreement, which is under negotiation this week. The PIPSC represents more than 15,000 scientists and researchers on the government payroll.

"The integrity of public science is at risk," PIPSC president Debi Daviau told CTV Ottawa on Tuesday.

Daviau said federal scientists are being "muzzled" and forced to make their work fit the government "ideology." She said that needs to change and scientists need to be permitted to speak to the media for the good of the public.

"Canadians need the facts and evidence in order to ensure the government has their best interest at heart," she said, adding that government researchers often focus on topics that university scientists do not address, such as food safety, drug testing and air quality.

"The public pays for this evidence, so it's rightfully theirs to have," she said.

Daviau said it's also important that scientists be permitted to attend conferences and speak to peers from other countries about their work.

"Collaboration really is the lifeblood of science, and if there's no collaboration happening, science can't really advance," she said.

The advocacy group Evidence for Democracy wants to push back against those government restrictions with the hope that scientists will be allowed to express themselves more freely under their next contract.

"It's really just about protecting the scientist's rights to actually do science," said Katie Gibbs, executive director of Evidence for Democracy. Gibbs is calling for the government to add a personal views exemption to its next contract with scientists, "so they can give their opinion, as long as they're being clear that it is their opinion," Gibbs told CTV’s Canada AM. She also wants those scientists to be allowed to share their work at scientific conferences and speak to the media more directly.

Gibbs says recently-introduced government policies have put up a barrier between federal scientists and the public, denying taxpayer-funded researchers the chance to speak to journalists in many cases. Last year, for instance, the federal government refused to let journalists speak to Environment Canada researchers on a UN climate change panel.

It is common practice for non-government researchers to make themselves available for interviews after publishing their work. However, the Government of Canada directs inquiries to its media relations wing, not its scientists, when a federal study is released.

Government scientists used to be free to answer journalists’ phone calls, Gibbs said. Now, reporters must submit a formal media request before they can do so, and there's a good chance that request will be denied due to political concerns.

She says it's not uncommon for government handlers to reject a media request before it even gets to the scientist. Sometimes the request is answered weeks later, long after the journalist's deadline has passed. Other times the journalist is only granted a written, pre-screened response, and is denied the chance to conduct a full interview.

"Some of these media requests have gone all the way up to the prime minister's office, deciding whether or not a scientist can speak to the media," Gibbs said.

University of Ottawa biology professor Scott Findlay says well-known anecdotal examples of restrictions on scientists generally tend to fall in one of two categories.

“One has to do with environmental science broadly construed, and in particular climate change,” Findlay told CTV’s Power Play. “But also on social justice type issues, on the social science side of the fence.”

A spokesperson for the Minister of State (Science and Technology) told CTV News that Canadian federal departments and agencies produce over 4,000 science publications per year. "While Ministers are the primary spokespersons for government departments, government scientists and experts are readily available to share their research with the media and the public," spokesperson Scott French said.

Treasury Board president Tony Clement dismissed the complaints, saying scientists have fielded “thousands” of media inquiries. He added that unions are attempting to “get headlines” and publicize their opening bargaining positions.

“But I’m quite confident we’re not doing the terrible things that they claim we are doing,” Clement said.

Recently retired biologist Steve Campana said previous governments have always had “controls in place,” when it comes to contact with the media, but those controls have increased considerably in the past five to 10 years.

“It’s reached a point where a scientist can publish the results of their scientific research … and although it’s out in the printed world, they’re actually not allowed to talk about it,” said Campana, who worked for the Department of Fisheries and Oceans.

“And I’m not talking about a situation here they talk about the policy or the implications or criticize the government in any way, I’m talking about it just the bare facts of the hard science.”

Echoing Gibbs, Campana told CTV’s News Channel that scientists must receive approval, which is often not “forthcoming.”

Several rallies took place on Tuesday, as demonstrators call for more freedom for government scientists in their next agreement.