Activists were shocked Tuesday night after officers let hundreds of them take over the city's downtown streets for the annual anti-police brutality march.
Previous editions of the March 15 event have turned nasty, featuring massive arrests, injuries to protesters and police as well as vandalized property and police cruisers.
This year, protesters didn't have a planned march route because most of them expected police to shut down the protest minutes after it started.
Instead, police on bicycles and in squad cars stayed well ahead of the mass of activists and protesters and closed streets ahead of marchers to clear their path.
"Hey guys!," yelled a masked woman into a megaphone at the end of the march. "When was the last time we had an anti-police brutality protest with no arrests?"
The crowd cheered.
There were no arrests, no tickets, and no reported damage to property, according to police.
Protesters take to the streets every year on March 15 to denounce what they claim is systematic racial and political profiling by the city's police force.
Activists say police officers regularly harass and abuse the homeless, activists and people who dress and act outside societal conventions.
Before the protest started, Olivier Racicot, 18, and Tommy Montmagny, 19, were cutting a white pillow case in half. Each side had a peace symbol drawn with black marker.
"This is not a protest against all police," Racicot said. "This is to show we have rights and we want to express ourselves the way we want and to denounce the police who are violent towards people."
Minutes later people strung up an effigy of a police officer with the head of a pig and began striking it with a stick, as if it were a pinata.
Activist Nick Harvest said the protesters were marching against police brutality in Montreal and across the world.
"The police institution is a tight-knit community and when they see officers (in other countries) commit murder and get off scot-free it shows other police officers they can push the envelop and commit horrendous acts of murder and get off," he said.
The march ended across the street from the old Forum with those taking part still left congratulating themselves for an evening with no arrests.
Activist Jaggi Singh said police shouldn't pat themselves too hard on the back for an incident-free protest.
"What should be considered normal is considered a surprise," he said, referring to the lack of arrests. "That reveals how extreme the police have been in the past. The mass arrests, the pepper spray. The police never apologized and we have never had justice for what they did."
Last year's event led to one arrest, while nearly 100 tickets were given out and several police cars were vandalized.
That march was declared illegal as soon as it began because organizers had not informed authorities of their route.
In 2014, five people were arrested, while 200 were detained a year earlier.