A federal committee is holding a hearing Wednesday into a complaint that the Canadian Security Intelligence Service illegally spied on peaceful anti-pipeline protesters in B.C., but the public may never know what has occurred behind the hearing's closed doors.

The security intelligence review committee hearing will not be open to the public.

The complaint was filed by the B.C. Civil Liberties Association (BCCLA) last year and alleges that CSIS "broke the law by gathering information on the peaceful and democratic activities of Canadians."

The association's executive director, Josh Paterson, said CSIS documents reveal the agency was watching people and groups opposed to pipeline expansion and that informants reported on, among other things, a gathering in a Kelowna church basement and the All Native Basketball Tournament in Prince Rupert.

"The information seems to have been shared between different agencies, including the RCMP, the National Energy Board and even to oil and pipeline companies," said Paterson. 

"That is not the job of Canada's spy and police agencies, to be reporting to corporations on the democratic activities of citizens."

Victoria retiree Terry Dance-Bennick will be testifying at the hearing Wednesday. She claims she was spied on while canvassing for the Dogwood Initiative, a group that opposes the Northern Gateway pipeline project. 

"A guy at the distance was photographing us with a big long telephoto lens," Dance-Bennick told CBC News. "It's scaring people from exercising their constitutional rights to freedom of speech and freedom of assembly."

Fear of terrorism

Andre Gerolymatis, a Simon Fraser University professor who specializes in international terrorism, thinks CSIS could have reasons that justify the surveillance. 

"The major fear for CSIS and the government is that pipelines represent a really good target for terrorists," said Gerolymatis in a phone interview.

"So what CSIS is doing — maybe not as well as they should — they're filming to see if anyone among the demonstrators … is affiliated with terrorists."

CBC News asked the security intelligence review committee for comment on the hearing but did not get a response.

In the past, CSIS has denied allegations that it acted illegally.

"While I cannot comment on specific complaints, what I can say is that CSIS investigates — and advises government on — threats to national security, and that does not include peaceful protest and dissent," said CSIS spokeswoman Tahera Mufti in a statement issued in February 2014.