In the APA manual 7th edition Appendix 7.1 (pp. 216 - 224), you will find many examples for citing legal and government sources. Here are a few.

Example for citing case law in text:

FORMAT: Cite the name of the case (italicized) and the year of the decision

Jenkins v. Taladega City Board of Education (1997)

(Jenkins v. Taladega City Board of Education, 1997)

Example for citing case law on the References page: 

FORMAT: Name v. Name, Volume Source Page (Court Date).

Jenkins v. Taladega, City Board of Education, 115 F. 3rd 821 (1997).

Example for citing a statute in text:

FORMAT: Give the popular or official name of the act (if any) and the year of the act.

Mental Health Systems Act (1988)

Example for citing a statute on the References page:

FORMAT: Name of Act, Volume Source § section number (year).

Mental Health Systems Act, 42 U.S.C. § 9401 (1988).

Americans With Disabilities Act of 1990, Pub. L. No. 101-336.