Opposition MPs and a prominent national security lawyer say the vacancies leave the Security Intelligence Review Committee weakened at a time of heightened public concern about civil liberties.
Deborah Grey, the committee's interim chairwoman, says she's anxiously awaiting the appointment of two new members to bring the committee up to full strength.
Currently the committee is operating with three members, including Grey — the minimum permitted under federal legislation.
Grey said in an interview that she has flagged the vacancies to senior government officials.
"I've had discussions with some folks to say, 'We need two more, and we look forward to them being appointed as soon as possible'."
The review committee, which has access to all CSIS records, studies the spy service's operations to ensure compliance with the law and also examines complaints from the public. It has absorbed some functions of the former inspector general's office, which was abolished by the Conservatives to save money.
In its latest plans and priorities report, the review committee says unfilled positions "have a direct impact on the organization’s ability to operate effectively."
At the moment, only one review committee member, Yves Fortier, can hear cases in French, Grey said.
"If we had another francophone, that would just be terrific," she said. "He's doing the work and he's doing it gladly, but if we share it around, it makes it that much easier on everyone."
The Conservative government introduced legislation Monday to solidify CSIS powers to track suspects overseas and more fully protect human sources.
The review committee is already overstretched and is not getting the co-operation from CSIS that it needs, says NDP deputy leader Libby Davies.
"The minister does know this," she said during the House of Commons question period.
In a report tabled Friday the review committee reported "significant delays" in receiving information from CSIS, Davies noted. In one case, the committee said it was "seriously misled."
Public Safety Minister Steven Blaney said he has full confidence in the committee's ability to fulfil its role.
"We have a strong and robust oversight," Blaney told the Commons. But he did not say when the vacancies might be filled.
Appointees to the review committee require top-secret security clearance, scrutiny that can take many months.
"That is not a quick process," said Grey, a former MP well known in federal circles.
"My life has been pretty public for years, but it still took months and months to go through the whole process. So we hope there's somebody in the hopper now, and they'll be appointed soon."
Toronto lawyer Paul Copeland said it's important to have "competent and diligent members" of the review committee with an interest in security intelligence matters.
"But this government doesn't seem to want to have meaningful oversight on CSIS."
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