From the OWL (Purdue's Online Writing Lab):
Great handouts from the Buxton Library:
The following information is needed :
Name v. Name, Volume Source Page (Court Date).
If you found the case online, you'll need to add the online information as well. Here's an example:
Lessard v. Schmidt, 349 F. Supp. 1078 (E.D. Wis. 1972). Retrieved May 1, 2008, from http://www.lawlibrary.state.mn.us/archive/supct/9807/c297168.htm