A group of 32 computer scientists have urged an appeals court in the US to block copyright claims over application programming interfaces (APIs) in the ongoing legal battle between Oracle and Google.

Representing the scientists, the Electronic Frontier Foundation (EFF) has submitted an amicus brief in the US Court of Appeals for the Federal Circuit.

Scientists said APIs that are open are critical to innovation and interoperability in computers and computer systems.

The group urges the court to uphold a decision from US District Judge William Alsup, who found that APIs are not copyrightable.

The group claimed that Oracle’s attempt to over-extend copyright coverage in its case against Google was irreconcilable with the purpose of copyright law and the nature of computer science.

EFF staff attorney Julie Samuels said that the law is already clear that computer languages are mediums of communication and aren’t copyrightable.

"Even though copyright might cover what was creatively written in the language, it doesn’t cover functions that must all be written in the same way," Samuels said.

"APIs are similarly functional – they are specifications allowing programs to communicate with each other. As Judge Alsup found, under the law APIs are simply not copyrightable material."

Oracle sued Google in 2010, alleging that the search engine firm’s Android mobile operating system had infringed its patents and violated its rights to the Java programming language.

The company alleged that Google copied the design specifications of about 37 APIs for Java’s core libraries into Android’s core libraries.