Oracle lost a patent and copyright case against Google last year when a Northern California District judge ruled that APIs, or “declaring code,” cannot be copyrighted. But Oracle is now appealing that decision, hoping that the "structure, sequence, and organization" of its Java APIs will be protected under copyright law.

On Friday, the Application Developers Alliance along with Rackspace, TMSOFT, and Stack Exchange filed an amicus brief in the appeals case, which is being heard by the US Court of Appeals for the Federal Circuit. (The Federal Circuit normally only hears patent cases, but it's taking on this copyright case because it was joined with patent infringement allegations by Oracle in the original case.) In the brief, the interested parties explain that for the past several decades, declaring code has been understood to be outside of copyright while implementing code is protected by copyright. “Were this Court to accept Oracle’s position, almost every player in the industry would be susceptible to suits for copyright infringement when using declaring code,” the brief states.

The group of developers also says that the court can't solve software developers' liability problems by allowing APIs to be copyrighted and then applying a fair use doctrine to determine whether they infringed. “If liability for the entire market were determined based on a case-by-case determination of fair use (an already unpredictable doctrine), developers would be unable to adequately predict their exposure.”

Since Oracle brought its appeal to the Federal Circuit in February of this year, Microsoft, EMC, and Netapp have together filed an amicus brief in favor of Oracle's position. The document states that without copyrighted APIs, the software industry would become destabilized.

Naturally, the signatories on this week's amicus brief disagree. “It's like using the + sign to mean addition,” wrote Joel Spolsky, chairman of the Application Developers Alliance Board of Directors and CEO and co-founder of Stack Exchange, in a press release on Friday. “Letting one company copyright APIs would be like letting one company have a monopoly on the use of the + sign. It's nothing more than a ridiculous, shameful attempt to abuse the legal system for the purpose of extortion.”