U.S. copyright law does not typically extend to works that are functional in nature. That was the basis of Alsup's argument, said Edward Naughton, an intellectual-property attorney and a partner with the law firm Brown Rudnick.

"Ultimately, he decided that the methods here, and the structure that Oracle was trying to protect by copyright ... was functional. Yes, he said it was creative and original, but insofar as it's functional, you can't protect it by copyright," he said.

Alsup indicated in his ruling that the patent laws would be a more appropriate way for Oracle to protect its APIs.

His ruling will be welcomed by many in the software industry, who feared a decision in Oracle's favor would set a worrying precedent that software APIs can be protected by copyright.

Such a finding would have stifled innovation, according to some. For example, companies have cloned the APIs used by Amazon Web Services in order to build interoperable cloud software platforms. Those companies might have hesitated before developing such products if a court had explicitly stated that APIs are eligible for protection.