Supreme Court decisions can be found in many places.
Find federal cases brought before a U.S. District Court or U.S. Court of Appeal.
Access to state court documents varies widely between states. Checking the state's official court records site is a good first step (search for county + court record search). Some courts may charge a per-page fee. In cases where records aren't digitized, call the county records office to inquire about mailing or faxing.