The Supreme Court decision is at: Mouvement laïque québécois v. Saguenay (City). The decision appears to be unanimous (9:0) provided I'm reading it correctly.
The state’s duty of religious neutrality results from an evolving interpretation of freedom of conscience and religion. The evolution of Canadian society has given rise to a concept of this neutrality according to which the state must not interfere in religion and beliefs. The state must instead remain neutral in this regard, which means that it must neither favour nor hinder any particular belief, and the same holds true for non‑belief. The pursuit of the ideal of a free and democratic society requires the state to encourage everyone to participate freely in public life regardless of their beliefs. A neutral public space free from coercion, pressure and judgment on the part of public authorities in matters of spirituality is intended to protect every person’s freedom and dignity, and it helps preserve and promote the multicultural nature of Canadian society. The state’s duty to protect every person’s freedom of conscience and religion means that it may not use its powers in such a way as to promote the participation of certain believers or non‑believers in public life to the detriment of others. If the state adheres to a form of religious expression under the guise of cultural or historical reality or heritage, it breaches its duty of neutrality. The Tribunal was therefore correct in holding that the state’s duty of neutrality means that a state authority cannot make use of its powers to promote or impose a religious belief. Contrary to what the Court of Appeal suggested, the state’s duty to remain neutral on questions relating to religion cannot be reconciled with a benevolence that would allow it to adhere to a religious belief.This seems so obvious to most people that it's a wonder why anyone ever thought that reciting prayers at city council meetings was justified.
Now, let's see how long it takes for other cities to stop the practice.
Hat Tip: Canadian Atheist