 In 1788 the Slave Trade Act 1788 was passed, partly in response to the "Zong" Massacre to ameliorate the conditions under which slaves might be transported (the Act would be renewed several times before being made permanent in 1799).In 1792 the House of Commons voted in favour of "gradual" abolition, and in 1807 parliament outlawed the African slave trade by legislation.This prevented British merchants exporting any more people from Africa, but it did not alter the status of the several million existing slaves, and the courts continued to recognise colonial slavery.