 Whether slavery was to be regulated under the new Constitution was a matter of such intense conflict between the North and South that several Southern states refused to join the Union if slavery were not to be allowed . Delegates opposed to slavery were forced to yield in their demands that slavery practiced within the confines of the new nation be completely outlawed . However , they continued to argue that the Constitution should prohibit the states from participating in the international slave trade , including in the importation of new slaves from Africa and the export of slaves to other countries . The Convention postponed making a final decision on the international slave trade until late in the deliberations because of the contentious nature of the issue . During the Convention 's late July recess , the Committee of Detail had inserted language that would prohibit the federal government from attempting to ban international slave trading and from imposing taxes on the purchase or sale of slaves . The Convention could not agree on these provisions when the subject came up again in late August , so they referred the matter to an eleven @-@ member committee for further discussion . This committee helped work out a compromise : Congress would have the power to ban the international slave trade , but not for another twenty years ( that is , not until 1808 ) . In exchange for this concession , the federal government 's power to regulate foreign commerce would be strengthened by provisions that allowed for taxation of slave trades in the international market and that reduced the requirement for passage of navigation acts from two @-@ thirds majorities of both houses of Congress to simple majorities . 
