The changes are included in Bill C-51's amendments to the Immigration and Refugee Protection Act, which have received little attention to date.
Security certificates allow the government to detain and deport permanent residents or foreign nationals considered to be a security threat using secret evidence that the accused is not allowed to see.
The bill states the government would only be required to disclose material that's "relevant to grounds of inadmissibility stated in the [security] certificate."
That contradicts key Supreme Court rulings on what the Crown must provide to the special advocates of people being held on the controversial certificates, say lawyers who have acted as special advocates.
"That [change] gives CSIS the power to decide what part of the file is going to be disclosed, and what part of the file is not going to be disclosed," says immigration lawyer Lorne Waldman.
"It will significantly alter the balance and the fairness of the procedure, a balance the Supreme Court has been very careful to craft."
Harkat, Charkaoui rulings pushed disclosure
In 2014, Waldman argued before the Supreme Court in the case of Mohamed Harkat, which yielded the latest in a string of Supreme Court rulings on security certificates.
In the Harkat case, as well as two prior rulings on the case of Adil Charkaoui, the Supreme Court upheld the certificates as constitutional, but sought to define a balance between the government and the defence lawyer for the accused, known as a special advocate.
In the case of Charkaoui, the court ruled the government must share all its information with the special advocate.
Waldman says the top court was also swayed by the Federal Court case of Hassan Almrei, another person detained for years on a security certificate. In his 2009 ruling, Justice Richard Mosely was highly critical of the government, saying the secret evidence later released to the special advocates contradicted the main evidence offered by CSIS in a public hearing.
The Almrei case in particular demonstrated that special advocates need access to all the information held by CSIS officials, Waldman says, not just what the spy agency chooses to reveal. And he says the new bill is an attempt to wind back the clock on the landmark Charkaoui ruling.
"The problem with [the new bill] is that it removes one of the only tools that the special advocates have for challenging the reliability of the secret evidence."
Toronto lawyer Paul Cavalluzzo served as one of the special advocates for Harkat. He says that in that case, the federal court found the government gave misleading information, which was only discovered after all the evidence was disclosed to special advocates.
Cavalluzzo adds that the top court ruled the government was too quick to hide information.
"As the Supreme Court of Canada said in the Harkat case, the government constantly over-asserts its national security privileges," he says.
"There's got to be very serious questions raised as to why they want to give less disclosure to the special advocates. Particularly in light of the fact that CSIS is now going to be engaged in far more disruptive behaviour than they have in the past."
A spokesperson for the Department of Public Safety said in an email that some of the amendments to the bill "are consistent with the Supreme Court's 2014 ruling in the Harkat case."
The spokesperson added that the government must sometimes rely on classified information in the case of security certificates, and that information "must be protected if its public disclosure would be injurious to national security or would endanger the safety of any person."
C-51 gives government new powers to appeal
Bill C-51 gives CSIS new powers to intervene in suspected terrorist activity, a departure from its previous role as gatherer of intelligence.
Cavalluzzo says the changes to security certificates in C-51 will undoubtedly lead to another court challenge.
"The present security certificate process is precarious as it is," he says. "To make it even [more unfair], in my view, is going to lead to constitutional challenges that will likely be successful."
Waldman adds that C-51 goes even further in muddying the waters around security certificates.
That's because of a provision that allows the government to appeal a judge's order to disclose information to the special advocate.
"So now they have the option of going to the Federal Court of Appeal, and asking the Federal Court of Appeal to review the decision to disclose."
Waldman argues this could bog down the proceedings even further, and says an equivalent power of appeal is not being granted to the special advocate.
He says that places the special advocate in an unequal position with regard to the process.