It's easy to get confused when trying to figure out how to cite a law in American Psychological Association style. The American Psychological Association has a special citation format for laws, which closely follows the style outlined in "The Bluebook: A Uniform System of Citation."
Federal, State or Local
Before creating the citation, figure out whether you have a federal, state or local law so that you can set up the citation properly.
When citing a federal law that is all in one place in the U.S. Code, include the name of the act with its original year, the section number, volume number, USC section number and the year of publication; for example, National Environmental Policy Act of 1969 § 102, 42 U.S.C. § 4332 (1994).
If the law is not all in one place, list the name of the law with original date, public law number, volume and statute page and the year of publication; for example, Americans with Disabilities Act of 1990, Pub. L. No. 101-336, § 2, 104 Stat. 328 (1991).
For a state law, include the name of the law if available, the state abbreviation, code abbreviation and the section number, followed by the year of publication; for example, Cal. Prob. Code § 141 (2012).
For any kind of law, your in-text citation should include the name of the law, if you have it, and the year; for example, Civil Rights Act (1964).
If you don't have the law's name, you can refer to it by its location in the U.S. or state/local code and section number. A law cited in this way does not need to be listed in the bibliography.