Why did southeners believe that dred Scott was free?

Southerners believed that Dred Scott was not free because they viewed him as property, not as a person entitled to rights. The prevailing legal framework at the time considered enslaved individuals to be the property of their owners, and the Supreme Court's 1857 ruling in the Dred Scott case reinforced this notion by declaring that enslaved people could not sue for their freedom. Additionally, many Southerners held the belief that the extension of slavery into new territories was essential for their economic interests, leading them to support the idea that Scott should remain enslaved.