Article 1, Section 9, Clause 4

Document 9

George Mason, Virginia Ratifying Convention

Mr. George Mason said, that gentlemen might think themselves secured by the restriction in the fourth clause, that no capitation or other direct tax should be laid but in proportion to the census before directed to be taken. But that when maturely considered it would be found to be no security whatsoever. It was nothing but a direct assertion, or mere confirmation of the clause which fixed the ratio of taxes and representation. It only meant that the quantum to be raised of each state, should be in proportion to their numbers in the manner therein directed. But the general government was not precluded from laying the proportion of any particular state on any one species of property they might think proper. For instance, if 500,000 dollars were to be raised, they might lay the whole of the proportion of the southern states on the blacks, or any one species of property: So that by laying taxes too heavily on slaves, they might totally annihilate that kind of property. No real security could arise from the clause which provides, that persons held to labour in one state, escaping into another, shall be delivered up. This only meant, that run-away slaves should not be protected in other states. As to the exclusion of ex post facto laws, it could not be said to create any security in this case. For laying a tax on slaves would not be ex post facto.

The Founders' Constitution
Volume 3, Article 1, Section 9, Clause 4, Document 9
http://press-pubs.uchicago.edu/founders/documents/a1_9_4s9.html
The University of Chicago Press

The Papers of George Mason, 1725--1792. Edited by Robert A. Rutland. 3 vols. Chapel Hill: University of North Carolina Press, 1970.