Oracle sued Google in 2010 for supposedly misusing its Java interfaces to create Android, an allegation that would be dismissed two years later by a California court. U.S. District Judge William Alsup ruled that software APIs are not copyrightable, saving Google’s mobile business and removing the Sword of Damocles hanging over the open source community. Or so we thought.

In an appeal hearing on Wednesday, Federal Circuit Judge Kathleen O’Malley questioned the search giant’s argument, pointing out that just because Java is free doesn’t mean it can’t qualify for copyright protection. “This would apply to every possible computer program out there,” O’Malley continued, highlighting that Aslup’s ruling indirectly gives Google the freedom to use APIs from competitors such as Apple and Microsoft.

Google attorney Robert Van Nest countered that the company did not copy any source code, adding that while the Android team could theoretically do so, “they would have to rewrite millions of lines of code” to pull it off.

Oracle is bent on winning a slice of Google’s Android revenues. Joshua Rosenkranz, the database giant’s attorney, asked the court to rule that Java APIs are subject to copyright and that Google was not entitled to a fair use defense. Van Nest said if the three-judge Federal Circuit panel does decide that patent law applies to APIs, a second jury should review the decision.

The tech industry is rife with intellectual property disputes. While EMC and Pure Storage are trading accusations over patent infringement and information theft, NetApp is going after Nimble Storage for allegedly engaging in anticompetitive behavior. The hybrid array is accused of luring former employees to “join the company and to take NetApp confidential information with them,” according to court documents.