The importation of slaves from overseas to the United States was prohibited in 1808, but criminal trafficking of enslaved people on a smaller scale likely continued for many years.
The most intensive periods of piracy were in the 1810s, before the U.S. Congress passed laws with massive fines and penalties including execution for illegal importers, and in the 1850s, when pro-slavery activists decided that the solution to rapid inflation in slave prices was simply to flood the market with humans abducted from across the ocean.
Despite the patrols and legal strictures on slave shipments from outside the United States, officials believed that trafficking of enslaved people from Africa, South America, and the Caribbean continued to at least some extent.
Reasons for this varied; some politicians wished to avoid repeating the impressment controversy which had been a cause of the War of 1812, while others, such as diplomat Nicholas Trist, covertly supported the trade.
"[7] Supreme Court Justice Joseph Story and Secretary of the Navy Paul Hamilton also asserted in public declarations that human trafficking from overseas continued.