The final text of the slave trade provision was designed to disguise what the Convention had done. The clause read: "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."
It is important to understand that the clause did not require an end to the trade in 1808. Moreover, it reflected the assumption, held by almost everyone at the Convention, that the Deep South would grow faster than the rest of the nation, and that by 1808 the states that most wanted to continue the trade would have enough political power, and enough allies, to prevent an end to it. Ending the trade would require that a bill pass both houses of Congress and be signed by the president. That process would give the supporters of the trade three opportunities to stop such a bill.
The slave trade provision was a significant factor in the debates over ratification, but its impact was complicated. Opponents of the Constitution, in both the North and the South, roundly condemned the clause. On the other hand, supporters of the Constitutioneven those who were ambivalent or hostile to slaverypraised it.
Northern supporters of the Constitution were at a rhetorical disadvantage in this debate, but they nevertheless had to engage the issue. They developed two tactics. The first, best put forth by James Wilson of Pennsylvania, was intellectually dishonest but politically shrewd. He argued that the slave trade clause would in fact allow for the end of slavery itself. In speeches he made the subtle shift from the "trade" to slavery, and since most of his listeners were not as legally sophisticated as Wilson, he was able to fudge the issue. Thus, Wilson told the Pennsylvania ratifying convention that after "the lapse of a few years... Congress will have power to exterminate slavery from within our borders."
Since Wilson attended all the debates over this clause, it is impossible to accept this statement as his understanding of the slave trade clause. More likely, he simply made this argument to win support for the Constitution. Supporters in Massachusetts and New Hampshire made similar arguments. In New Hampshire, a supporter of the Constitution also argued that the slave trade clause gave Congress the power to end slavery. A more sophisticated response to the trade was to note that, without the Constitution, the states could keep the trade open indefinitely because the Congress under the Articles of Confederation had no power to regulate commerce, but under the Constitution it would be possible, in just twenty years, to end the international slave trade. These arguments led northerners to believe that the Constitution required an end to the trade after 1808, when in fact it did not.
Upper South supporters of the Constitution, such as James Madison, also made the argument that a ban on the trade was impossible under the Articles, and thus the Constitution, even if imperfect, was still a good bargain. Deep South supporters, like General Charles Cotesworth Pinckney, simply bragged that they had won a great victoryas indeed they hadin protecting the trade for at least twenty years. In summing up the entire Constitution, Pinckney, who had been one of the ablest defenders of slavery at the Convention, proudly told the South Carolina House of Representatives: "In short, considering all circumstances, we have made the best terms for the security of this species of property it was in our power to make. We would have made better if we could; but on the whole, I do not think them bad."