Preventing slavery in Canada was very important to the people of the British colonies.   Fighting international slavery was a social activist  movement  akin to environmentalism today. The Presbyterian church of York, now Toronto, was  outspoken about ending  forever the pernicious practice.   They believed it violated principles of human justice and violated God's laws of how the world is ordered.  Slavery played no part in the economy of the colonies, so passing laws to against  slavery was relatively easy.