Slavery and the United States Constitution
Although the United States Constitution did not use the words "slave" or "slavery", it dealt directly with American slavery in at least five provisions and indirectly protected the institution elsewhere in the document. Background
At the time of the drafting of the Constitution in 1787, and its ratification in 1789, slavery was banned by the states in New England and Pennsylvania and by the Congress of the Confederation in the Northwest Territory, by the Northwest Ordinance. Though slaves were present in other states, most were forced to work in agriculture in the South. According to H. W. Brands, because of the declining productivity of crops like tobacco due to soil exhaustion, many of the drafters of the Constitution assumed that slavery would naturally die out in the South as it had done in industrialized North. This changed after the adoption of the Constitution, with the invention of the modern cotton gin in 1793, which provided a more sustainable and economically viable crop for Southern plantations. Historical debate
Throughout U.S. history there have been disputes about whether the Constitution was proslavery or antislavery. James Oakes writes that the Constitution's Fugitive Slave Clause and Three-Fifths Clause "might well be considered the bricks and mortar of the proslavery Constitution". "But", Oakes adds, "there was also an antislavery Constitution.... Congress was granted the power to make 'all needful rules and regulations' for the territories, and for decades after ratification hardly anyone doubted that this authorized the federal government to ban slavery from the territories.... Then there was the familiar assertion that the principle of fundamental human equality was embodied in the Constitution.... Doesn't the Preamble state that the purpose of the federal government was to 'secure the blessings of liberty' ... ? Similarly, the Fifth Amendment declares that 'no person' could be deprived of life, liberty, or property without due process of law." Oakes continues: "Throughout the decades-long debate over slavery and the Constitution some of the most contentious issues arose over constitutional principles that cannot be found in the actual wording of the Constitution. Nowhere does the Constitution state that Congress cannot 'interfere' with slavery or abolition in a state, yet it was widely agreed that it could not. Nor does the Constitution expressly recognize a right of 'property in man'.... Given that the Constitution was the handiwork of men who disagreed about slavery, it is hardly surprising that it could be—and was—read as both proslavery and antislavery." Oakes' view is that, "depending on which clauses you cite and how you spin them, the Constitution can be read as either proslavery or antislavery". Frederick Douglass
In The Constitution of the United States: is it pro-slavery or anti-slavery?, Frederick Douglass cites the Notes of Debates in the Federal Convention of 1787 left behind by James Madison in order to describe four provisions of the Constitution that are said to be pro-slavery. In examining the history of how the clauses were debated and structured, he argues either that they are not pro-slavery or that they do not concern slavery. He argues that the Three-Fifths Clause (Article I, section 2) "deprives [slave] States of two-fifths of their natural basis of representation"; that the Migration or Importation Clause (Article I, section 9) allowed Congress to end the importation of slaves from Africa in 1808; that the Fugitive Slave Clause (Article IV, section 2) does not apply to slaves but rather to "Person[s] held to Service or Labour", which do not include slaves, because a slave "is a simple article of property. He does not owe and cannot owe service. He cannot even make a contract"; and that the clause giving Congress the power to "suppress Insurrections" (Article I, section 8) gives Congress the power to end slavery, "[i]f it should turn out that slavery is a source of insurrection, [and] that there is no security from insurrection while slavery lasts...."

See also
 Three-fifths Compromise
 Act Prohibiting Importation of Slaves
 Fugitive Slave Act of 1793
 Fugitive Slave Act of 1850
 Dred Scott v. Sandford
 Thirteenth Amendment to the United States Constitution
 Abolitionism in the United States
 The Constitution of the United States: is it pro-slavery or anti-slavery?, by Frederick Douglass

References

Slavery in the United States
United States constitutional law

Further reading
 Balkin, Jack M. and Levinson, Sanford (2023). "Frederick Douglass as Constitutionalist". Maryland Law Review, forthcoming. Belz, Herman (1998). Abraham Lincoln, Constitutionalism, and Equal Rights in the Civil War Era. New York: Fordham University Press. Cover, Robert M. (1975). Justice Accused: Antislavery and the Judicial Process. New Haven and London: Yale University Press. Douglass, Frederick. (1860) FREDERICK DOUGLASS, “THE CONSTITUTION OF THE UNITED STATES: IS IT PRO-SLAVERY OR ANTI-SLAVERY?”, full text. Abridged
Farber, Daniel (2003). Lincoln's Constitution. Chicago and London: The University of Chicago Press. Finkelman, Paul (2016). "Frederick Douglass's Constitution: From Garrisonian Abolitionist to Lincoln Republican". Missouri Law Review, vol. 81, no. 1, pp. 1-73. Finkelman, Paul (2018). Supreme Injustice: Slavery in the Nation’s Highest Court. Cambridge, Massachusetts and London, England: Harvard University Press. Review
Maltz, Earl M. (2009). Slavery and the Supreme Court, 1825-1861. Lawrence, Kansas: University Press of Kansas. McGinty, Brian (2008). Lincoln and the Court. Cambridge, Massachusetts and London, England: Harvard University Press. Review, JSTOR
Moreno, Paul D.; O'Neill, Johnathan, eds. (2013). Constitutionalism in the Approach and Aftermath of the Civil War. New York: Fordham University Press. Neely, Jr., Mark E. (2011). Lincoln and the Triumph of the Nation: Constitutional Conflict in the American Civil War. Chapel Hill, NC: University of North Carolina Press. Radan, Peter (2023). Creating a More Perfect Slaveholders' Union: Slavery, the Constitution, and Secession in Antebellum America. Lawrence Kansas: University Press of Kansas. Rebeiro, Bradley (2023). "Frederick Douglass and the Original Originalists". Brigham Young University Law Review, vol. 48
Waldstreicher, David (2009). Slavery's Constitution: From Revolution to Ratification. New York: Hill & Wang. Wiecek, William W. (1977). The Sources of Antislavery Constitutionalism in America. Ithaca and London: Cornell University Press. Wood, Gordon S. (Jan. 12, 2021). "Was the Constitution a Pro-Slavery Document? ", The New York Times (review of James Oakes, The Crooked Path to Abolition)