In 1790, the Pennsylvania Abolition Society engaged in an unprecedented lobbying campaign to abolish slavery. Their efforts faced intense opposition from most southern congressmen, who blocked any attempt to abolish an institution that was important to their plantation economy. After a contentious debate, congressional leaders put the proposals aside without voting on them, setting a precedent in which Congress generally avoided discussing slavery. Congress passed two acts related to slavery during the Washington administration: the Fugitive Slave Act of 1793, which made it a federal crime to assist an escaping slave, and established the legal system by which escaped slaves would be returned to their masters; and the Slave Trade Act of 1794, which limited the United States' involvement in the transportation of slaves by prohibiting the export of slaves from the country.