OTTAWA - The federal government has launched a sweeping review of a crumbling anti-terrorist law, acknowledging the system needs fixing, The Canadian Press has learned.

"We are working on it actively, very actively, and recognize that the current situation is not ideal -- and that there is a need for change," Peter Van Loan, Canada's public safety minister, said in an exclusive interview.

The review of the rickety national-security certificate system could scrap or revamp a law used to arrest and deport non-Canadians considered a threat to national security.

Certificates have existed for three decades, and more than two dozen have been issued since 1991, when they became part of federal immigration law.

But legal challenges and upbraidings from judges over miscues by Canada's spy agency have seen recent cases slow to a crawl -- or collapse altogether.

"I'm contemplating what we would do in the future, and whether that is an appropriate instrument," Van Loan said.

"I'm taking a serious look at it, trying to work our way through what the implications of the court decisions are and how we can balance that with our ability to assure the national security of Canadians."

The government has initiated just six certificate cases -- four terror suspects, a hatemonger and an alleged Russian spy -- since the 9-11 attacks on the United States.

But for critics, the deportation tool has come to symbolize the worst excesses of the fight against Islamic extremism.

Opponents say the process is fundamentally unfair because detainees are not given full details of the allegations against them.

A case involving Montrealer Adil Charkaoui, a native of Morocco, fell apart recently when the government withdrew supporting evidence, saying its disclosure would reveal sensitive intelligence sources and methods of the Canadian Security Intelligence Service.

A judge's demand for information in the Charkaoui case "pushed us beyond what we could accept," CSIS director Richard Fadden said in an October speech.

Charkaoui, a French teacher and father of three, wants compensation for his six-year ordeal.

"I think strongly that any country must defend their own interests against terrorism, against any threat," he says, "but they must do it in (a) very fair way."

Four active cases range from seven to 10 years old, illustrating the legal limbo that certificates can create for detainees.

Mahmoud Jaballah and Mohamed Zeki Mahjoub, both Egyptian, were arrested in 1999 and 2000 respectively, while Hassan Almrei of Syria was detained one month after Sept. 11, 2001, and Mohamed Harkat of Algeria seven years ago this month.

But even if the courts find the certificates to be valid, it's unclear whether the men could be deported because each says he has reason to fear being tortured if forced back to his homeland.

The Supreme Court of Canada has ruled that such suspects can be deported to face a risk of torture only if they pose an exceptional risk to national security.

All four men have been granted release from prison under strict conditions that control virtually their every move while the cases play out in the Federal Court of Canada.

RCMP Commissioner William Elliott says security certificates have become a means of controlling terror suspects from abroad "when there really isn't anywhere to send them."

"They're here indefinitely, but there has been a series of decisions by courts which have given those individuals more and more liberty," Elliott said in an interview with The Canadian Press.

Canada has tried to get assurances that terror suspects won't be mistreated, he noted. "But if you have a country that tortures people, you've got to really wonder about how good their word is. So it's a problem. I'm glad we're not in the lead on it."

If the government ever argues before a judge that certificates are a good means of detaining someone indefinitely, the whole scheme will be struck down as unconstitutional, said Craig Forcese, a national-security law expert who teaches at the University of Ottawa.