Why was there a court case about Dred Scott?

The case of Dred Scott v. Sandford was first heard by the Supreme Court on February 11–14, 1856, and reargued on December 15–18, 1856. Dred Scott’s lawyers reiterated their earlier argument that because he and his family had resided in the Louisiana territory, Scott was legally free and was no longer enslaved.

The Dred Scott case, also known as Dred Scott v. Sandford, was a decade-long fight for freedom by a Black enslaved man named Dred Scott. The case persisted through several courts and ultimately reached the U.S. Supreme Court, whose decision incensed abolitionists, gave momentum to the anti-slavery movement and served as a stepping stone to the Civil War.

Explanation:

https://www.history.com/topics/black-history/dred-scott-case

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