The act affected only the import or export of slaves, and did not affect the internal trade in states or between states. During the American Revolution all thirteen colonies prohibited their involvement in the slave trade, but three states later passed legislation legalizing it again. protected a state's involvement in the Atlantic slave trade for twenty years from federal prohibition. Article 5 said this clause could not be affected by constitutional amendment. Only starting January 1, 1808, could there be a federal law to abolish the international slave trade in all states, although individual states could and did ban it at any time.