What did the supreme court decide in the Dred Scott decision?

In the Dred Scott v. Sandford decision of 1857, the Supreme Court ruled that enslaved African American Dred Scott could not sue for his freedom because he was not considered a citizen under the Constitution. The Court also declared that Congress lacked the authority to prohibit slavery in the territories, effectively nullifying the Missouri Compromise. This decision heightened tensions over slavery in the United States and is often cited as a catalyst for the Civil War.