For more than 20 years, the prevailing view has been that application program interfaces (APIs) are unprotectable elements of copyrighted computer programs. According to this view, programmers are free to reimplement other firms' APIs in independently written code. Competition and innovation in the software industry has thrived amazingly well in part because of rulings upholding this understanding.
Challenging this view is the Court of Appeals of the Federal Circuit (CAFC) May 2014 decision in Oracle v. Google. The CAFC held that the "structure, sequence, and organization" (SSO) of the Java APIs that Google reimplemented in its Android software are protectable expression under copyright law. It reversed a lower court ruling that the Java APIs were not copyrightable.