There have been a few queries recently regarding referencing case law. If you look at the APA referencing guide you can find examples of this on pages 26-27.
Case law is not included in reference lists or bibliographies at all, however on the first mention of a case in an assignment a full citation is needed in this format:
Parties to the case [year] Volume number Abbreviation for name of report First page of report
R v Gloucestershire County Council, Ex parte Barry  AC 584
For subsequent mentions in text just use the parties involved. For example:
…as stated in R v. Gloucestershire County Council, Ex parte Barry…
… the case of R v. Gloucestershire County Council, Ex parte Barry demonstrates that…
If you haven’t read the original case then you will need to do secondary referencing so it would look like this in text:
R v Gloucestershire County Council, Ex parte Barry  AC 584 cited in Brammer (2010)
The details of the book (in this example the chapter in an edited book) you have read the case law in would be included in the reference list:
Brammer, A. (2010). Community care and the promotion of independence. In L-A. Long, J. Roche, & D. Stringer (Eds.), The law and social work contemporary issues for practice (2nd ed., pp. 211-223). Basingstoke: Palgrave Macmillan.