Slavery Abolition Act , (1833), in British history, act of Parliament that abolished slavery in most British colonies, freeing more than 800,000 enslaved Africans in the Caribbean and South Africa as well as a small number in Canada . It received Royal Assent on August 28, 1833, and took effect on August 1, 1834.

Several factors led to the Act’s passage. Britain’s economy was in flux at the time, and, as a new system of international commerce emerged, its slaveholding Caribbean colonies—which were largely focused on sugar production—could no longer compete with larger plantation economies such as those of Cuba and Brazil . Merchants began to demand an end to the monopolies on the British market held by the Caribbean colonies and pushed instead for free trade . The persistent struggles of enslaved Africans and a growing fear of slave uprisings among plantation owners were another major factor.

Legal challenges to slavery in British North America

British abolitionists had actively opposed the transatlantic trade in African people since the 1770s. (Several abolitionist petitions organized in 1833 alone collectively garnered the support of 1.3 million signatories.) Such antislavery views spread to Upper Canada (later Canada West), influencing the passage there of the 1793 Act to Limit Slavery, the first such legislation in the British colonies.

In the eastern colonies of Lower Canada (what is now Québec), Nova Scotia, and New Brunswick, however, abolitionist attempts had been unsuccessful. In 1793, for instance, Pierre-Louis Panet introduced a bill to the National Assembly to abolish enslavement in Lower Canada, but the bill languished over several sessions and never came to a vote.

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Instead, individual legal challenges first raised in the late 1700s undermined the institution of enslavement in these areas. One important case arose in February 1798, when an enslaved woman named Charlotte was arrested in Montréal and refused to return to her mistress. She was brought before James Monk, a justice of the King’s Bench with abolitionist sympathies, who released her on a technicality. According to British law, enslaved persons could be detained only in houses of corrections, not common jails, and no houses of correction existed in Montréal. Charlotte and another enslaved woman named Judith were accordingly freed that winter. Monk stated in his ruling that he would apply this interpretation of the law to subsequent cases. Another significant 1798 case came before the courts in Annapolis Royal, Nova Scotia, when a local military officer, Frederick William Hecht, sought to establish his title to an enslaved woman named Rachel Bross. After a lengthy trial, the jury rejected Hecht’s claim, ruling instead that Bross was a free servant.

Rulings in such cases did not always favour emancipation, however. Only two years after the trials of Charlotte and Bross, an enslaved woman named Nancy petitioned for her freedom in the New Brunswick courts. Fourteen years earlier, Nancy had run away with her son and three others, but they were caught and returned to her owner, a farmer and loyalist settler named Caleb Jones. The challenge filed by her attorneys was that slavery was a socially accepted custom but was not officially recognized in New Brunswick. The judges’ decision was split, and Nancy remained enslaved.