What was the major issue that kept dred Scott from getting his freedom?

The major issue that kept Dred Scott from gaining his freedom was the Supreme Court's ruling in the 1857 case Dred Scott v. Sandford, which declared that African Americans, whether free or enslaved, could not be considered U.S. citizens and thus had no legal standing to sue in federal court. Additionally, the Court ruled that Congress had no authority to prohibit slavery in the territories, effectively nullifying the Missouri Compromise. This decision reinforced the institution of slavery and denied Scott his claim to freedom based on his time spent in free territories.