On March 2, 1807, President Jefferson signed a bill to abolish slave trade.  The congressional debates surrounding this bill show how legislators found it hard to cope with moral issues as they competed with commercial interests in the abolition of the importation of slaves In a nutshell, the bill found commercial and legal concerns taking precedence over the moral and humanitarian issues around the slave trade. Trade continued and grew within the United States.
The invention of the cotton gin impacted slave trade beyond the vision of this bill, also slaves continued to be illegally smuggled into ports like Charleston, S.C. being sold privately. Across the Atlantic Ocean slavery remained legal in most of the British Empire until the Slavery Act of 1833.
Britain used its international strength to put pressure on other nations to end their own slave trade. Britain created fines for captains that continued with the trade. The fines could be up to 100 pounds per slave found on a ship. Captains would sometimes dump slaves overboard when they saw Navy ships coming in order to avoid these fines.  The Royal Navy controlled the world’s seas,and established the West African coast as an area to board ships.