The massive Oracle v. Google litigation has entered a new phase, as Oracle filed papers (PDF) yesterday saying it will appeal its loss on "fair use" grounds to the US Court of Appeals for the Federal Circuit.

For a brief recap of the case: after Oracle purchased Sun Microsystems and acquired the rights to Java, it sued Google in 2010, saying that Google infringed copyrights and patents related to Java. The case went to trial in 2012. Oracle initially lost but had part of its case revived on appeal. The sole issue in the second trial was whether Google infringed the APIs in Java, which the appeals court held are copyrighted. In May, a jury found in Google's favor after a second trial, stating that Google's use of the APIs was protected by "fair use."

Oracle's appeal is no surprise, but it will be a long shot. The four-factor "fair use" test is a fairly subjective one, and Oracle lawyers will have to argue that the jury's unanimous finding must be overturned. There are various ways a jury could arrive at the conclusion that Google was protected by fair use.

Oracle's post-trial motions, which the district court judge rejected , indicate the tack it might try to take on appeal. It could focus on jury instructions that it viewed as improper, or Oracle could simply argue that the evidence presented at trial was so overwhelming that no reasonable jury could have found in Google's favor.

The case will go back to the Federal Circuit, the same appeals court that decided APIs could be copyrighted in the first place. That decision overruled US District Judge William Alsup, the lower court judge, and was extremely controversial in the developer community. However, the same decision that insisted APIs can be copyrighted clearly held the door open to the idea that "fair use" might apply. Unless Oracle pulls off a stunning move on appeal, its massive legal expenditures in this case will be for naught.