A series of climate change protests that shut down major roads around the globe on Monday saw demonstrators arrested in some cities, but no arrests made in others.

The Extinction Rebellion protest shut down traffic on Edmonton's Walterdale Bridge from 7 a.m. to just after 8 a.m.

Police convinced participants to break the blockade early and frustrated drivers were eventually allowed to proceed.

No charges were laid at the scene but police indicated the incident was still under investigation and charges could be laid at a later date. Police did not have an update on possible charges Tuesday.

At a similar protest in Montreal, three people were arrested after they climbed a bridge and unfurled a banner calling for action on climate change.

Police said the they were arrested because their safety was in jeopardy.

In Toronto, police made 20 arrests despite calling the protests peaceful and in Vancouver, police arrested 10 people who refused to leave a downtown bridge after receiving warnings.

Edmonton Police Chief Dale McFee said police did not arrest protesters on the Walterdale Bridge because the protest wrapped up relatively quickly, but that didn't stop some residents from calling on officers to break up the protest with force.

"In Canada, all people have the right to gather peacefully. There are however limitations to peaceful assemblies contained in various sections of the criminal code," said McFee.

The Charter of Rights and Freedoms does state that all Canadians have the freedom of peaceful assembly and freedom of expression, with limits.

However, a spokesperson for the Canadian Civil Liberties Association says it all comes down to whether those limits are reasonable.

'Protests, to be effective, have to be disruptive'

"Courts have said generally that unless what they call a breach of the peace is taking place during a protests, which usually would involve some level of violence, that there should be the right to protest," said Cara Zwibel, director of the CCLA's Fundamental Freedoms Program.

According to the Criminal Code of Canada, a protest can turn unlawful if it "disturbs the peace tumultuously" or provokes others to disturb the peace.

Since the Edmonton protest did not engage or provoke violence, Zwibel said it's just part of living in a democratic country.

"I think that's something in a democracy we should be tolerant of," she said. "I understand that people feel inconvenienced and upset, they feel the law is being broken, but the reality is often protests, to be effective, have to be disruptive."

While police have the ability to arrest protesters a number of different grounds, including municipal bylaws or provincial highway laws, Zwibel said "arresting someone for engaging in completely lawful activity is not something that you can do."

Supreme Court ruling

She said a Supreme Court of Canada ruling that came out last week has entrenched that fact.

The unanimous Oct. 4 decision ruled that police do not have the power to arrest protesters simply to prevent violence or disorder.

It spun out of an Ontario court case after police arrested a man at a counter-protest in 2009 despite the fact that he did not commit an offence.

Randy Fleming argued that police violated his charter right to expression and used excessive force, and the court agreed.

At Monday's protest, police warned the group that they could be arrested if they continued, eventually convincing them to pack up early and avoid being arrested.

"If you don't have that negotiation up front, you tend to get something jammed in a court process," said McFee. "I think it's important that our folks, the way they acted, I thought they did it quite well. It didn't mean that we wouldn't move to the other action." 

According to the City of Edmonton, local traffic bylaws do not cover disruptive events, which are handled by Edmonton police.