Tens of thousands of demonstrators took to the streets of Montreal to mark 100 days of student protests and defy a new law requiring that organizers give notice of demonstrations eight hours in advance. The law and subsequent protest grew out of weeks of student demonstrations against plans to raise university tuition fees, in which clashes have erupted between police and protesters, with hundreds arrested. The protest against the so-called “truncheon law” on Tuesday was mostly peaceful and unfolded in a festive atmosphere despite scattered incidents in which protesters shattered three shop windows. However, police used batons and stun grenades to break up a smaller demonstration of around 2,000 people later Tuesday night. Police said they arrested 50 people at the later protest for “illegal assembly” and wearing masks, which are banned at demonstrations, after some protesters threw bottles at the riot police. The provincial government has defended the law, which requires organizers of demonstrations of more than 50 people to submit detailed plans to police at least eight hours advance under penalty of heavy fines.