The court itself has recognized that the XIII, XIV, and XV Amendments were designed to change the Fed/state balance of power, affording the Fed govt the authority to develop and implement a plan for moving toward freedom and equality for Black Americans.
The purpose of these Amendments: to provide congress with authority to enforce and implement the Amendments’ rights.

Both the 14th Amend, which prohibits slavery, and the 15th Amend, which guarantees all citizens the vote, include a provision like the 14th Amend’s – 5, stating that “Congress shall have power to enforce, by appropriate legislation, the provisions of this article.” Relying on this language, Congress has asserted its power in each of these “enforcement” provisions to enact legislation beyond the boundaries of rights defined by the Court.
NOTE: Congress in asserting its power of enforcement as stated in the 14th Amendment needs only comply with the NECESSARY and PROPER CLAUSE provided in Art. 1 – 8