During the Reconstruction period, several government actions asserted federal supremacy. Key actions included:
- The passage of the Civil Rights Act, which mandated enforcement of civil rights across the entire United States.
- The adoption of a series of amendments—most notably the 13th, 14th, and 15th amendments—that required states to protect the rights of African Americans and established federal oversight in these matters.
These actions reinforced the federal government's authority over state laws and practices, particularly in relation to civil rights and the protection of newly freed slaves.