From the Columbia Electronic Encyclopedia:
black codes, in U.S. history, series of statutes passed by the ex-Confederate states, 1865–66, dealing with the status of the newly freed slaves. They varied greatly from state to state as to their harshness and restrictiveness. Although the codes granted certain basic civil rights to blacks (the right to marry, to own personal property, and to sue in court), they also provided for the segregation of public facilities and placed severe restrictions on the freedman's status as a free laborer, his right to own real estate, and his right to testify in court. Although some Northern states had black codes before the Civil War, this did not prevent many northerners from interpreting the codes as an attempt by the South to reenslave blacks. The Freedmen's Bureau prevented enforcement of the codes, which were later repealed by the radical Republican state governments.