In African American history, the Dred Scott decision represents a really low point. It represents the degree to which African Americans were not respected by white Americans and by the law in the antebellum period.
The Dred Scott decision was a very low point for African Americans. It held that African Americans were not citizens of the United States. It held that they had no rights that white people had to respect. In that sense, it was a very bad decision for African Americans. It made their inferior status (even for free blacks) a matter of official law. The Supreme Court of the United States, which was supposed to be a symbol of justice, had ruled in a very unjust way on black rights.
However, the decision did, in a sense, help to improve things for African Americans. It did help to bring about the Civil War. This war, of course, caused slavery to end.
The Dred Scott decision is seen as a major blot on American history because of how unfairly it treated African Americans.