The correct answer to this open question is the following.
The Supreme Court helped erode African Americans' freedom with its decision on the Dred Scott case and its decision in 1883 of declaring the Civil Rights Act of 1875, unconstitutional.
These decisions severely hurt the civil rights of African Americans in the United States. The Supreme Court also added that the US Congress lacked the authority under the 14th Amendment to give protection to African Americans and that the states were the ones that had the authority to do so.