Q. Should a law cited in APA be included with other citations at the end of a paper in alphabetical order?

Yes, your reference list should be alphabetized. 

The proper format is: 

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

*Providing the URL isn't required, but will help the reader retrieve the law/act

Example: 

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

That would be listed in your bibliography alphabetically under: Mental.

This is drawn from the 7th edition of the APA Manual, Ch. 11.5.