In the wake of this week's attacks in Saint-Jean-sur-Richelieu, Que., and Ottawa, the Conservative government is looking at bringing in new laws to crack down on pro-ISIS sentiments like those posted to Quebec assailant Martin Couture-Rouleau's Facebook page, CBC News has learned.

The move to tighten Canada's Criminal Code is expected to come as part of a sweeping overhaul of Canada's national security regime.

Earlier this week, RCMP Supt. Martine Fontaine told reporters investigators simply didn't have enough evidence to arrest Couture-Rouleau, despite concerns over his possible radicalization.

"We did not have enough evidence to charge him and to detain him," she noted.

'Radical thoughts' not a crime in Canada: RCMP

She said investigators followed up with his family and the imam at his local mosque, but had no reason to think or evidence to show that he would commit a crime on Canadian soil.

'We could not arrest someone for having radical thoughts. It's not a crime in Canada."

It's not clear how the government would go about extending the current laws to cover those who go public with their support for ISIS and other suspected extremist groups without raising the ire of free-speech advocates — and possibly constitutional lawyers, as well, depending on the specific approach it takes.

A spokeswoman for Justice Minister Peter MacKay declined to provide any specific details on what new measures may be under consideration. 

"Our government is exploring options to build on our record to better equip our security agencies and law enforcement with the tools they need to intercept threats and ultimately convict those who pose a danger to Canadian families and communities," Jennifer Geary told CBC News.

'No law can possibly deter hateful thoughts'

Several MPs voiced concern over what former Conservative-turned-Independent MP Brent Rathgeber described as the "particularly problematic" idea of regulating thought and expression.

"No law can possibly deter hateful thoughts from those who think them," he told CBC News. "Prohibitory laws will never be tantamount to mind control."

He notes that there are already laws against inciting hatred through calls to action.

"If one is opposed to the Israeli actions in Gaza, does that make her an anti-Semite? If one is against Operation Impact, is that a 'pro-ISIS sentiment'?" he wondered, referring to the U.S.-led military mission targeting ISIS in Syria and Iraq.

"This is a very slippery slope … and is going to have to be dispassionately and reasonably debated."

He said the response from Conservative parliamentary secretary Roxanne James during question period on Friday has left him less than optimistic that such a discussion is likely to happen.

"I see little evidence the government is interested in a collaborative approach, which is unfortunate given what is at stake and the outpouring of fraternalism and solidarity that we evidenced yesterday."

Speaking with reporters outside the House, NDP justice critic Francoise Boivin said the government already spends millions to have CSIS "spy on the internet."

"It's very hard to control hate," she said.

Liberal MP Marc Garneau said he, too, wants to see any bill before deciding whether to support it.

"We live in a country where we have a lot of respect for people's rights and freedoms, and at the moment, as many people have said, if you think something bad, it's not sufficiently cause for arrest," he said.

"Now, if you write something down that's widely disseminated, that's a more complicated dimension."

Conservative MP Rob Clarke, a former RCMP officer, was doubtful the online distribution of material promoting extremist ideologies like ISIS could be stopped entirely.

"You see how the availability of the internet is to everyone around the country and in the world ... It's probably very difficult."

Online hate speech section revoked

The government could find itself on the defensive over last year's decision to back a Conservative private member's bill to remove online hate speech from the Canadian Human Rights Act, and to strip the federal human rights commission's power to investigate complaints.

At the time, the government argued the CHRA was not the appropriate avenue to deal with hate speech and said it would bolster the Criminal Code provisions on hate speech instead.

Most opposition MPs voted against the bill, which nevertheless passed with the full support of the government.

Under the current criminal laws, anyone found guilty of inciting hatred against an identifiable group — which the Criminal Code defines as "any section of the public distinguished by colour, race, religion, national or ethnic origin, age, sex or sexual orientation" —  can be sentenced to up to two years in prison.

The government's proposed anti-cyberbullying bill, which is currently before the Senate, would expand that list to include mental and physical disabilities.

It would also extend the power of the court to seize and remove online material that promotes genocide.

But those changes seem unlikely to apply to the sort of pro-ISIS messaging that the Conservatives reportedly want to shut down.

Even before this week's attacks, the government was looking at the role of the internet in radicalizing Canadians.

Earlier this month, Public Safety Canada put out a call for research proposals on how violent extremist groups use the internet to recruit new members.

The bid notice said "a better understanding of the role of the internet as a communications medium is crucial, given how it may play roles to both advocate and to counter narratives of violent extremism."

With files from CBC News