NDP Leader Tom Mulcair's comments that the deadly actions taken by Michael Zehaf-Bibeau should not be characterized as terrorism has sparked a debate among his political rivals and highlighted a controversy often ignited when using such terms.

"We cannot look at an act of violence on its own and immediately declare it is terrorism or not, we have to take into account context — motivation and intent, victim, perpetrator, etc," said James Forest, professor and director of the graduate program in security studies at the University of Massachusetts Lowell. "And as with many things in life, different aspects of context will undoubtedly be interpreted differently by different people."

For his part, Mulcair suggested Zehaf-Bibeau, 32, had committed a "criminal act" and that based on the shooter's past, there wasn't enough evidence to describe his actions as terrorism.

"When you look at the history of the individual, attempts to get help, even to be in prison to get help if that turns out to be the case, I think that we're not in the presence of a terrorist act in the sense that we would understand it," Mulcair said.

The remarks were immediately seized upon by Conservative MPs, including Prime Minister Stephen Harper, who said there was "no contradiction in individuals who may have a series of personal financial and mental difficulties, and also be engaged in terrorist jihadist activities."

Liberal Leader Justin Trudeau agreed and referenced the RCMP, who have said Zehaf-Bibeau's actions were motivated by political ideology. A source familiar with the investigation has told CBC News that a video recovered by the RCMP appears to show Zehaf-Bibeau making specific reference to Canada's foreign policy as motivation for his actions and that he praises Allah in the recording.

But is this an incidental factor, as Mulcair suggested, and is the real root of Zehaf-Bibeau's motivation his major dependency and mental health issues?

Lorne Dawson, a University of Waterloo sociology professor and co-director of the Canadian Network for Research on Terrorism, Security and Society, says no.

Lashed out in 'politically significant way'

While acknowledging Zehaf-Bibeau's drug and mental health issues, Dawson pointed out that he also decided to lash out in a "very politically significant way — at least symbolically."

"It may be wise in the end to interpret him as yet another victim of jihadi terrorist groups, since they are purposefully seeking to exploit the vulnerabilities of people like him. But his actions constitute terrorism in their nature and their consequences, whether he fully understood that or not."

Forest agreed that Zehaf-Bibeau's personal issues don't mitigate whether he committed a terrorist act.

"When an individual commits a non-terrorist act of homicide, do we call it something other than murder if it turns out he/she also had major drug issues, mental health issues, etc. at the time of their crime?"

"The fact that there was a political ideology motivating the attack separates it from other kinds of murderous violence that stem from homicidal lunacy, passion, profit or personal revenge," Forest said.

Whatever mental distress Zehaf-Bibeau was suffering, it doesn't exclude the reality of what he did and what he specifically attacked, said Michael Zekulin, a political science professor who studies terrorism and radicalization at the University of Calgary.

Justin Bourque, 24, of Moncton, could be facing three consecutive life sentences, with no chance of parole for 75 years for the fatal shooting of three RCMP officers. Experts don't agree on whether his actions should be considered terrorist acts. (Facebook)

"This is a political statement, a symbolic statement. If he's simply mentally distressed and wants to kill people, he could have killed people at the shelter he was staying at, he could have gone to a mall, he could have shot people in the street. He specifically went to and targeted a member of the Canadian military and then he moved specifically to the institutions of government."

What about Bourque?

Under Canada's Criminal Code, terrorism is defined as a violent act committed "in part for a political, religious or ideological purpose, objective or cause" with the intention of "intimidating the public, or a segment of the public, with regard to its security, including its economic security, or compelling a person, a government or a domestic or an international organization to do or to refrain from doing any act."

How one defines an "ideological purpose," however, and whether other acts should also be considered terrorism are often debatable.

For example, there's the case of Justin Bourque, who fatally gunned down three RCMP officers in Moncton, N.B. earlier this year. He was charged with first-degree murder, but no terrorism-related offences, even though his sentencing hearing heard that he was trying to start a rebellion against what he considered to be an oppressive corrupt government that he insisted was squelching the freedom of most Canadians.

Zekulin acknowledged that Bourque's case is a grey area, and that different experts would split on how to classify his actions.

"But the argument here is, where is the greater political statement? With him at this this point, it is less clear or less cut and dry as it is with both Mr.[Martin] Couture-Rouleau or Mr. Zehaf-Bibeau."

"I would still look at [Bourque's case] more as the personal [motivation] of 'I hate the police, I hate government.' It's not an effort to impact or effect large-scale political change."