The three-fifths rule for counting slaves is often misunderstood. When the Constitutional Convention debated the issue of how to count population for the purposes of representation, the Southern delegates to the Convention would have been pleased if nonvoting slaves had been counted as full persons. That way, the Southern states would have had a greater representation in the House of Representatives. In contrast, some Northern delegates resisted counting slaves at all. Why, asked Elbridge Gerry, “shd. the blacks, who were property in the South, be in the rule of representation more than the cattle & horses of the North?” Among other things, counting slaves provided an incentive to import still more slaves.

Nor was the three-fifths rule new at the Convention. It was derived from a mechanism adopted in 1783 to apportion requisitions (the national government’s only revenue source under the Articles of Confederation) among the states. That rule was intended to provide rough equality between the North and the South, and when the idea first appeared at the Convention, no one suggested that another fraction would be more appropriate. Indeed, the rule was included in a June 11 motion, made by James Wilson of Pennsylvania and seconded by Charles Pinckney of South Carolina, suggesting that a compromise had already occurred behind the scenes.

By itself, however, the three-fifths compromise for representation was not enough. Facing deadlock at the Convention, Gouverneur Morris (representing Pennsylvania) moved on July 12 to add a “proviso that taxation shall be in proportion to Representation” (later limited to direct taxation), the purpose of which, wrote James Madison, was to “lessen the eagerness on one side, & the opposition on the other, to the share of Representation claimed by the [Southern] States on account of the Negroes.” Morris subsequently said he meant his motion only “as a bridge to assist us over a certain gulph,” but tying apportionment to both taxation and representation turned out to be crucial. Slaves were to be counted as less than whites for representation, which was not in the interests of the South. Slaves were, however, also to be counted as less than whites for measuring a state’s apportioned direct-tax liability, and that was a benefit to the South. A fuller account of how the Framers handled this sensitive matter requires looking as well at the Direct Taxes Clause (Article I, Section 9, Clause 4) and at other clauses of the Constitution dealing with slavery (Article I, Section 9, Clause 1; Article IV, Section 2, Clause 3; and Article V).

Furthermore, the compromise protected the integrity of the census, as Madison explained in The Federalist No. 54, “the States should feel as little bias as possible to swell or to reduce the amount of their numbers. . . . By extending the rule to both [taxation and representation], the States will have opposite interests which will control and balance each other and produce the requisite impartiality.”

The three-fifths rule does not directly affect litigation today, but it affects how scholars interpret the apportionment requirement for direct taxes. It has been argued, for example, that the clauses dealing with direct taxation should be ignored because they are tainted by slavery, or because, with slavery ended, there is no longer reason to honor any part of the compromise. In light of the entire history that led to the Revolution and the Constitution, however, it would go too far to assume that in a world without slavery, the Founders would have been indifferent to the dangers of national taxation.

Furthermore, understood in context, the three-fifths apportionment rule was not necessarily proslavery in principle, for even though slaves were property under the laws of the Southern states, the Constitution itself acknowledged that they were persons. In addition, by tying both representation and direct taxation to apportionment, the Framers hoped to remove any sectional benefit, and thus any proslavery taint, from the special counting rule. In fact, the slave states despised having to give in and accept the Direct Taxes Clause as part of the price of obtaining the three-fifths counting rule.

No one at the time knew that the direct tax requirement would be weakened by Supreme Court interpretation, and few understood that the three-fifths rule would yield such extraordinary political dividends for the slave states. Many scholars have pointed out that the three-fifths rule provided Southern States significant political advantages in the House of Representatives and the Electoral College, and thus also in the choice of President and the appointment of members of the Supreme Court until the election of Abraham Lincoln and the coming of the Civil War. But at the Constitutional Convention, the Framers believed that they had crafted a workable compromise.