Series of four acts passed by the U.S. Congress (1870–75) to protect the rights guaranteed to blacks by the 14th and 15th Amendments to the Constitution of the United States .
The acts authorized federal authorities to penalize any interference with the registration, voting, officeholding, or jury service of blacks. Violations produced over 5,000 indictments and 1,250 convictions throughout the South. The Supreme Court later ruled sections of the acts unconstitutional.