The Interstate Slave Trade 1

When the Constitution was ratified in 1789, it contained two provisions that related to Congress’s power over the slave trade. The first, the Commerce Clause (Article I, Section 8, Clause 3), provided (and still provides) that Congress had the power to “regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.”

The Commerce Clause, of course, did not specifically refer to slavery or the slave trade. It was clear, however, to the delegates to the Constitutional Convention that it might impact the slave trade. For this reason, the delegates also adopted a clause that restricted the power of Congress to meddle with the slave trade until 1808. This clause, which I will refer to as the “1808 Clause” (Article I, Section 9, Clause 1), stated:

The Migration or 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.

In his book Slavery and the Commerce Power: How the Struggle Against the Interstate Slave Trade Led to the Civil War (Yale University Press 2006), David L. Lightner points out that the scope of the 1808 Clause is ambiguous. The ambiguity centers on the meaning and implication of the terms “Migration” and “Importation.” For example:

-- Were the terms meant to differentiate between the carrying of slaves between or among states (“Migration”) and the bringing in of slaves from outside the country (“Importation”)?

-- Or were the terms meant to differentiate between the immigration of free whites (“Migration”) and the bringing in of slaves (“Importation”)?

-- Or were the words simply synonyms, both of which were intended to connote the bringing in of slaves from outside the country?

Whatever the precise scope of the 1808 Clause, that Clause appears to provide powerful support for the proposition that the Founders understood that the Commerce Clause extended to the interstate slave trade, as well as to the international slave trade – and that Congress had the power after 1808 (if not before) to restrict or even ban interstate slave trading.

Even if we attribute the most restrictive meaning to the 1808 Clause – that it barred only the importation of slaves, nor their transfer from state to state – it demonstrates that the founders understood that slave trading was “Commerce with foreign Nations” within the meaning of the Commerce Clause. Otherwise, why go to the trouble of carving it out? And if international slave trading was a species of “Commerce” potentially subject to Congressional regulation, there is no textual reason to believe that interstate slave trading was not likewise “Commerce” that Congress could regulate.

Finally, the 1808, however construed, would seem to put to rest the possibility the founders did not understand that the power to regulate included the power to ban altogether. It was presumably precisely because the founders believed the contrary to be true that they restricted Congress’s ability to ban (at least) the importation of slaves from abroad before 1808.

In sum, the textual evidence provides overwhelming support for the proposition that the Constitution gave Congress the power, after 1808 if not before, the ban the interstate transportation and sale of slaves.

And yet, there is also powerful reason to wonder whether anyone understood this. Although most of the evidence is negative, it is striking that no one at the Constitutional Convention so much as mentioned that the Commerce Clause gave Congress the power to strangle the institution of slavery by banning the interstate slave trade. It is even more striking that no southern antifederalist tried to indict the Constitution on the same grounds. Nor did any northerner support or oppose the Constitution on these grounds.

As Professor Lightner summarizes the record, there is “spotty” evidence that a handful of men might have dimly perceived the issue. But it is clear that “it never entered the minds of most southerners that the Constitution gave Congress the authority to outlaw the interstate slave trade.”

Incredibly, southerners apparently did not recognize the danger to slavery presented by Congress’s ability to regulate interstate commerce for almost twenty years:

Not until 1807, when Congress moved toward exercising its acknowledged power to ban the importation of slaves from abroad beginning in 1808, did it dawn upon some southern representatives in Congress that there was a danger of federal intervention in the domestic slave trade.

It is to that episode that we will turn next.