Groups of protesters built pyres from plastic traffic cones and construction materials, setting them ablaze in the middle of an intersection in a popular night club district.
Meanwhile, the protest has spread beyond borders.
In New York, members of the Montreal-based rock band "Arcade Fire" wore the movement's iconic red squares during an appearance with The Rolling Stones' Mick Jagger on Saturday Night Live. Jagger wore a red shirt, but no red square.
A day earlier, players in Quebec's film industry were sporting them at the Cannes Film Festival.
The scenes in Montreal unfolded during a tense late night march that, on several occasions, saw riot police use tear gas and protesters throw bottles and rocks.
Student protesters were joined by others spilling out of bars and clubs.
Together, they built the fires and cheered as the flames lit up the streets and sent plumes of black smoke billowing into the night sky.
A young woman, kneeling and handcuffed with some others who had been arrested and penned on a sidewalk patio, summed up the bizarre scene.
"I'm drunk! I've been on a patio all evening!" she told police, in an exchange caught on the live broadcast of Concordia University Television.
Some bystanders accused police of using excessive force on a crowd whose members were mostly peaceful. Riot police charged protesters and repeatedly warned that they would be incarcerated throughout the weekend unless they dispersed.
The night ended with more than 50 arrests.
Just one day earlier the Quebec government passed emergency legislation designed to end the months of unrest.
Montreal police said they were trying to figure out how to use Bill 78 without heightening tensions.
"We don't want to cause a commotion, we want to prevent one," spokesman Ian Lafreniere said Saturday afternoon.
But the new law appeared only to embolden protesters.
The chants from marchers were mostly directed at Premier Jean Charest and the police rather than the tuition hikes that first prompted the nightly marches.
At the same time, protesters were already finding creative ways around the controversial legislation.
In an attempt to avoid hefty fines, one prominent student group took down its web page Saturday that listed all upcoming protests. Another anonymous web page with listings quickly popped up in its place _ with a note discouraging people from attending.
The disclaimer is meant to evade new rules applying to protest organizers, who must provide an itinerary for demonstrations and could be held responsible for any violence.
The website also accepts submissions for future protests and suggests using a software that blocks a sender's digital trail.
In another online manoeuvre, the website for the Quebec Liberal Party and the province's Education Ministry were down for most of Saturday in an apparent cyber attack.
While no one claimed responsibility, the hacker group Anonymous has taken an interest. The group wrote on Twitter that Bill 78 "must die" and later issued a video denouncing the law.
Bill 78 lays out strict regulations governing demonstrations of over 50 people, including having to give eight hours' notice for details such as the protest route, the duration and the time at which they're being held.
Failure to comply could bring stiff fines for the organizers, but the law could be difficult to enforce.
Protests like Saturday's have begun in the same downtown square at 8:30 p.m. every night for nearly a month. There's no clear organizer, and the protest routes have been determined by the marchers on a street by street basis.
Still, the law says student associations that don't encourage their members to comply with the law could face punishment. Fines range between $7,000 and $35,000 for student leaders and between $25,000 and $125,000 for student unions or student federations.
The City of Montreal also adopted a new bylaw Friday that threatens protesters who wear masks with heavy fines. Lafreniere said it gives police "another tool'' to deal with the demonstrations. But it failed to deter dozens of protesters from wearing masks Saturday night.
After facing heavy criticism from legal experts and civil liberties groups, the Quebec government took steps Saturday to defend Bill 78 by taking out full page ads in the local newspapers.
The headline read, "For the sake of democracy and citizenship.''
An opinion poll released Saturday suggested the majority of Quebecers support the new measures. The survey, however, was taken before the specifics of the legislation were known.
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