In her annual report tabled Thursday, Information Commissioner Suzanne Legault said the integrity of the system is at risk and the weaknesses must be urgently addressed.
The Access to Information Act allows people who pay $5 to request a variety of records from federal agencies — from correspondence and briefing notes to expense reports and audits.
The government is supposed to respond within 30 days or provide good reasons why a delay is necessary.
But Legault said staff shortages meant one institution — the RCMP — routinely went six months without even acknowledging receipt of requests.
In other cases, the response time could vary from 18 months to more than three years.
Legault, an ombudsman for users of the access law, said the mild optimism she felt last year has evaporated.
"In fact, there are unmistakable signs of significant deterioration in the federal Access to Information system," Legault told a news conference.
In 2012-13, complaints to her office from requesters were up nine per cent overall. Administrative complaints about such things as delays, time extensions and fees were up 42 per cent.
The trend has continued into this fiscal year, she said.
"It is imperative that the access problems be fixed promptly and significantly. There is truly a need for leadership on the part of the government and the individual institutions."
The comments amounted to a clear shift in Legault's tone from measured concern to blunt criticism of the government's record.
NDP ethics critic Charlie Angus characterized the commissioner's assessment as "some of the strongest language we've ever seen from a parliamentary officer."
"We're talking about denying access to Canadians about how money is being spent."
Despite the alarm bells, Treasury Board President Tony Clement, minister responsible for Access to Information, defended the government's record on handling a growing number of requests as "very, very good."
"We take the law seriously, and of course we'll always look for ways to do better."
Legault said it was unfortunate that the speech from the throne delivered this week "is silent on matters of transparency and accountability."
The throne speech mentioned the government's commitment to address issues surrounding the fatal rail disaster in Lac-Megantic, Que., last summer, she noted.
However, based on Access to Information request extensions being taken by Transport Canada, members of the public who want records about federal plans to deal with the accident's aftermath can expect to wait "a year before they actually get their response," she said.
"Canadians have a quasi-constitutional right to most government-held information and they should have a prerogative to request what they want to see, when and how — not when the government chooses to release the information."
Clement said Thursday that a record 54,000 requests were answered last year, with six million pages of information released.
"We are responding. We are being open and transparent, and that is the record that these statistics speak to," he said after question period in the House of Commons.
Legault took issue Thursday the minister's oft-repeated claims, saying that the number of requests being handled is meaningless when there are egregious delays.
"That's not transparency, that's simply breaching the law."
Legault said she recently met with Clement and told him she would publicly hold him accountable for the Access to Information system's failings.
Deputy ministers and agency heads — as well as Privy Council clerk Wayne Wouters, who oversees them — must also answer for the way organizations answer access requests in order to have "a public service that respects its legal obligations," Legault said.
Clement said he had asked his deputy minister to look into one of Legault's ideas — a rapid-response team that can parachute into departments that become suddenly swamped with access requests when a hot issue arises.
"If there are some staffing issues that we can deal with, we can deal with those," he added.
To mark the law's 30th anniversary, Legault will soon table recommendations to modernize the legislation, drafted in the pre-Internet era.
She confirmed she will advise government to extend the law to cover Parliament and administration of the courts.
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