Before 1867, when Canada became a self-governing country, Canada was still British North America, colonies within the British Empire.

It would be this entity that would deal with the question of what to do with escaped slaves. Slavery existed in Canada even during the era of New France (1600s-1763), and continued after the Conquest -- though not at the scale it was in America.

I recently posted a reply dealing with the situation in Upper Canada (Ontario), which actually began the process of banning slavery in the colony -- the first act of its kind in the British Empire:

/u/enygma9753

https://www.reddit.com/r/AskHistorians/comments/e8bpi6/do_we_have_any_accounts_or_information_on_the/fcpbz8a?utm_medium=android_app&utm_source=share

When Britain enacted the Slavery Abolition Act in 1833, this banned slavery throughout the empire.

Canada was long considered the final stop on the Underground Railroad: the network of routes, safe houses and transports that abolitionists used to help slaves find freedom north of the US border. Blacks still experienced discrimination, unfairness in wages and land distribution, intolerance and abuse despite these newfound rights in Canada. This would be especially disappointing to those slaves who took up arms for Britain to fight the US, in order to secure their freedom.