Final answer:
Chief Justice Roger Taney used the justification that enslaved people are not citizens to defend the Supreme Court's decision.
Step-by-step explanation:
Chief Justice Roger Taney used the justification that enslaved people are not citizens to defend the Supreme Court's decision. In the landmark case of Dred Scott v. Sandford in 1857, Taney argued that enslaved people, regardless of whether they were brought into free territories, were not entitled to the rights and privileges of American citizens. This ruling further solidified the institution of slavery and denied enslaved people the opportunity to seek freedom through the legal system.
Learn more about Dred Scott v. Sandford