New powers for Canada's spy agency are unconstitutional and represent an extraordinary reversal of the traditional role of the judiciary, two national groups say in a newly filed legal challenge of the Conservative government's omnibus security bill.

The Canadian Civil Liberties Association and Canadian Journalists for Free Expression are asking Ontario's Superior Court of Justice to hear their constitutional case against the federal anti-terrorism measures, commonly known as Bill C-51.

The legislation, which recently received royal assent, gives the Canadian Security Intelligence Service more power to thwart suspected terrorist plots — going well beyond its long-standing information-gathering role.

The legislation also creates a new offence of promoting the commission of terrorist offences and broadens the government's no-fly list powers. In addition, it greatly expands the sharing of federally held information about activity that "undermines the security of Canada."

In a joint statement, the two organizations challenging the law said Tuesday that key elements violate the Canadian Charter of Rights and Freedoms "in a manner that is not justified in a free and democratic society."

The Conservatives brought in the bill to fight homegrown extremism after two Canadian soldiers were murdered last October just days apart by lone, jihad-inspired killers.

The government and its senior officials have consistently defended the legislation as constitutional.

"This bill is crafted with very reasonable measures," Public Safety Minister Steven Blaney said Tuesday in Vancouver.

"I leave it to the court to make their own view and analysis of the bill. We're pretty confident that this bill is there for the right reason, to protect Canadians, and that it will stand any challenge that it could face."

'No due process, no fundamental justice'

Civil libertarians and privacy advocates have strongly opposed giving CSIS the power to derail suspected plots — for instance, by meddling with computers, cancelling airline reservations or carrying out even riskier operations.

With its new mandate, CSIS needs "reasonable grounds to believe" there is a security threat before taking measures to disrupt it.

The spy agency would require a court warrant whenever proposed disruption measures violate the Charter of Rights or otherwise breach Canadian law.

The notice of application in the court challenge says the measures amount to "an extraordinary inversion" of the time-honoured role of the courts and the principles of fundamental justice by asking the judiciary, and not Parliament, to authorize limits on charter rights "as opposed to protecting such rights and preventing their violation."

The legal challenge objects to someone being added to the no-fly list "on mere suspicion" he or she might commit an act that threatens an airplane.

"Once placed on the no-fly list, it is very difficult for the individual to remove their name from the list," the court filing says. "There is no due process, no fundamental justice, and no natural justice under the scheme."

The application also says the concept of activity that "undermines the security of Canada" is unconstitutionally vague and leaves a person in the dark as to whether information about — or related to them — has even been shared.

In addition, the provision outlawing promotion of terrorist offences has "a chilling effect on freedom of expression and association" and encourages people to remain silent "rather than risk the perils of prosecution," the application charges.