The general databases listed below are all good starting points for locating briefs. Other good strategies are browsing the website of the organization that filed the brief or the website of the court where it was filed.
For example, the U.S. Department of Justice (Appellate Courts, Supreme Court), the ACLU, and the American Intellectual Property Law Association all provide briefs they have filed online. LLRX provides a longer list of organizations that typically post their briefs online here.
Likewise, the Ninth Circuit and First District Courts of Appeal make some electronic documents available online. You can locate other courts using Find My Court and the 1999 Union List of of Court Records or learn more using our Docket Information & Court Filing Guide.