Listening to a podcast of Simon Schama who is going all over the place in talking about the abolition of slavery, I found this little bit. Jefferson did pass a law banning the importation of slaves. I do recall, when this anti-slavery aspect of Jefferson was raised that I've heard it argued that such things made slavery even worse. Slaves went from being moderately prices commodities, easily replaceable, to increasingly amortized assets, all the more fitting for the later application of the Fugitive Slave Act.
Nevertheless, here's a bit of Jefferson's act.
Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That from and after the first day of January, one thousand eight hundred and eight, it shall not be lawful to import or bring into the United States or the territories thereof from any foreign kingdom, place, or country, any negro, mulatto, or person of colour, with intent to hold, sell, or dispose of such negro, mulatto, or person of colour, as a slave, or to be held to service or labour.
SEC 2. And be it further enacted, That no citizen or citizens of the United States, or any other person, shall, from arid after the first day of January, in the year of our Lord one thousand eight hundred and eight, for himself, or themselves, or any other person whatsoever, either as master, factor, or owner, build, fit, equip, load or otherwise prepare any ship or vessel, in any port or place within the jurisdiction of the United States, nor shall cause any ship or vessel to sail from any port or place within the same, for the purpose of procuring any negro, mulatto, or person of colour, from any foreign kingdom, place, or country, to be transported to any port or place whatsoever, within the jurisdiction of the United States, to be held, sold, or disposed of as slaves, or to be held to service or labour: and if any ship or vessel shall be so fitted out for the purpose aforesaid, or shall be caused to sail so as aforesaid, every such ship or vessel, her tackle, apparel, and furniture, shall be forfeited to the United States, and shall be liable to be seized, prosecuted, and condemned in any of the circuit courts or district courts, for the district where the said ship or vessel may be found or seized.
What is particularly curious about this law is that it is a direct refutation of the Constitutional compromise baked in Article One - Section Nine which states the following:
The Migration and Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person.
A bit of cheesey legalese saying in 1787 that the slave trade cannot be impinged upon by Congress for 20 years. Well, there's the featherbedding right there. And it is Jefferson who makes sure that Congress moves as soon as it's Constitutional to outlaw the trade.
I didn't know that.