A good way to find cases about copyrights is to start with a relevant copyright statute section. Title 17 of the U.S. Code in either Lexis or Westlaw provide annotations and citation features. Case Notes in Lexis or Notes of Decisions in Westlaw provide summaries of prominent cases. You can also use Shepherd's in Lexis or the Citing References tab in Westlaw to find additional cases that cite that code section.