Final answer:
The Dred Scott Decision negatively affected the Abolitionist Movement, denying African Americans citizenship and civil rights, and undermining efforts to limit the spread of slavery by declaring the Missouri Compromise unconstitutional.
Step-by-step explanation:
The Dred Scott Decision had several negative impacts on the Abolitionist Movement in the United States. First, the Supreme Court's ruling that African Americans could never be citizens meant that they had no legal standing to sue, thus denying their basic civil rights and weakening the legal arguments that abolitionists could use to fight against slavery. Secondly, by declaring the Missouri Compromise unconstitutional, the decision opened the door for the extension of slavery into previously free territories, confronting abolitionists with the stark reality that their efforts to limit the spread of slavery were not supported by the highest court.