Const. Stéfanie Trudeau, 40, made headlines last spring after she was caught on video pepper-spraying protesters during the student demonstrations.
Trudeau was arrested last night at her home in Longueuil after a complaint was filed by Montreal police. The details of that complaint have not been made public.
She has not been charged with any offence.
Officer 728, as she became known, was suspended with pay in October after an internal police review.
Another video later came to light showing Trudeau putting a man in a headlock during an arrest.
As part of the conditions of her release, Trudeau agreed to spend 15 days in a Sherbrooke hospital. Her lawyer said outside of court that his client is not well.