The United States Constitution, Article 1, Section 9, prohibited Congress from banning the importation of slaves until the year 1808. A bill to do this was first introduced in Congress by Senator Stephen Roe Bradley of Vermont in December 1805, and its passage was recommended by President Jefferson in his annual message to Congress in December 1806. In March 1807, Congress passed the legislation, and President Thomas Jefferson signed it into law on March 3, 1807. Subsequently, on March 25, 1807, the British Parliament also passed an act banning the slave trade aboard British ships.
The effective date of the new federal law (January 1, 1808) was celebrated in New York City by the oration and program reprinted here. The state of New York had banned the importation of slaves in 1788; and it pursued a policy of gradual abolition that freed all slaves in New York by 1827, although outsiders were legally entitled to hold slaves temporarily under a “nine-months” law in effect until 1841. The 1807 Act applied only to the importation of slaves from abroad, and did not end the domestic slave trade, which remained legal until the Emancipation Proclamation in 1863 (for the seceded states) or the Thirteenth Amendment in 1865 (for the slave states that remained in the Union). The text of the 1807 Act is online at http://www.yale.edu/lawweb/avalon/statutes/slavery/sl004.htm
The Oration by Peter Williams, Jr., is among the earliest publications by an African American on the subject of abolition. Williams (c.1780–1840) was born in Brunswick, New Jersey, and attended the African Free School in New York. His mother was an indentured servant from St. Kitts, and his father was a veteran of the Revolutionary War who had helped establish the first African Methodist Episcopal Zion Church in 1796. Williams, Jr., later organized St. Philip’s African Church in Harlem in 1818, and in 1826 he became an Episcopal clergyman. He was active in the New York African Society for Mutual Relief and the American Anti-Slavery Society. A brief biography of him is online at the New-York Historical Society: http://www.slaveryinnewyork.org/PDFs/Life_Stories.pdf
Available at: http://works.bepress.com/paul_royster/67/