Dred Scott (c.1795-1858), a slave in Missouri, had been taken by his owner, John Emerson, into Illinois, where slavery had been prohibited by the Northwest Ordinance of 1787, and into the Louisiana Territory, where slavery was forbidden by the MISSOURI COMPROMISE.

After his return to Missouri, Scott brought suit (1846) against Emerson's widow, claiming that he was free by reason of his residence in free territory. The Missouri supreme court ruled against him, but after his ownership was transferred to Mrs. Emerson's brother, John F. A. Sanford (the name was misspelled in legal records) of New York, Scott brought a similar suit in federal court. The decision of the Supreme Court of the United States in Dred Scott v. Sandford (1857) held that a black slave could not become a citizen under the U.S. Constitution based on that Scott had not become free by virtue of his residence in a territory covered by the Missouri Compromise, since that legislation was unconstitutional.

This was viewed as a proslavery decision by the abolitionists, and the case probably hastened the coming of the Civil War. That issue aside, it was the second time that the Court had declared an act of Congress unconstitutional, the first having occurred 54 years earlier, in MARBURY V. MADISON.

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This information comes from "Dred Scott," By Robert J. Steamer, Academic American Encyclopedia. Grolier Electronic Publishing, Danbury, 1995.