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Employment discrimination law in the United States derives from the common law, and is codified in numerous state and federal laws, particularly the Civil Rights Act 1964, as well as in the ordinances of counties and municipalities. These laws prohibit discrimination based on certain characteristics or protected categories. The United States Constitution also prohibits discrimination by federal and state governments against their public employees. Discrimination in the private sector is directly constrained by the Constitution, but has become subject to a growing body of federal and state law. Federal law prohibits discrimination in a number of areas, including recruiting, hiring, job evaluations, promotion policies, training, compensation and disciplinary action. State laws often extend protection to additional categories or employers.