Congressional and executive enforcement.
As its first enforcement legislation, Congress passed the Civil Rights Act of 1866, guaranteeing black Americans citizenship and equal protection of the law, though not the right to vote. The amendment was also used as authorizing several Freedmen's Bureau bills. President Andrew Johnson vetoed these bills, but Congress overrode his vetoes to pass the Civil Rights Act and the Second Freedmen's Bureau Bill.
Proponents of the Act, including Trumbull and Wilson, argued that Section 2 of the Thirteenth Amendment authorized the federal government to legislate civil rights for the States. Others disagreed, maintaining that inequality conditions were distinct from slavery. Seeking more substantial justification, and fearing that future opponents would again seek to overturn the legislation, Congress and the states added additional protections to the Constitution: the Fourteenth Amendment (1868) defining citizenship and mandating equal protection under the law, and the Fifteenth Amendment (1870) banning racial voting restrictions.
The Freedmen's Bureau enforced the amendment locally, providing a degree of support for people subject to the Black Codes. Reciprocally, the Thirteenth Amendment established the Bureau's legal basis to operate in Kentucky. The Civil Rights Act circumvented racism in local jurisdictions by allowing blacks access to the federal courts. The Enforcement Acts of 1870 & 1871 and the Civil Rights Act of 1875, in combating the violence and intimidation of white supremacy, were also part of the effort to end slave conditions for Southern blacks. However, the effect of these laws waned as political will diminished and the federal government lost authority in the South, particularly after the Compromise of 1877 ended Reconstruction in exchange for a Republican presidency.
