The Oyez Project has provided streaming audio of Supreme Court arguments since 1996, but it recently took a leap forward by adding Supreme Court audio in MP3 format. The first set of releases, which can be found here, includes 51 cases. They are release under a Creative Commons license that allows listeners to download, share and create derivative works using these audio files.
The OYEZ Project continues to provide streaming access to more than 2,000 hours of Supreme Court audio. It includes all audio recorded in the court since 1995 and selective audio before then. The project’s aim is to create a complete collection of all audio since 1955.