Google suffered a heavy blow by losing a multi-billion dollar lawsuit on the use of its Android operating system.

Oracle won its appeal with the federal appeals court in a suit where it alleged that Google's use of the Android operating system is an infringement of the intellectual property that it owns.

The ruling emphasized that the programming interfaces in the Java technology by Oracle can be protected under U.S. copyright law. Oracle further alleged that Google has relied on the copyrighted interfaces in making its popular Android mobile operating system.

With this decision, Oracle can now continue to pursue its legal claim against Google. The case was referred back to the U.S. District Court in San Francisco, where the two tech giants will battle to protect their own interests.

The case began four years ago when Oracle sued Google for infringing on patents and copyrights which were related to the Java technology created by Oracle. Specifically, Oracle claims that Google copied the structure, sequence and organization of Java application programming interfaces, or APIs, in creating Android.

However, despite the jury agreeing that Google indeed used some of Oracle's APIs in Android, they were unresolved on whether such usage is protected by the fair use law which in limited conditions allows copying. A different jury will have to decide on whether the use of APIs was protected.

In its defense, Google argued that the use of APIs should not be copyrighted under U.S. law because developers who are creating interactional software programs need access to them. A District Court judge had previously agreed with this assertion. However, U.S. Court of Appeals for the Federal Court ruled in favor of Oracle on Friday.

Oracle remains confident that the district court will "appropriately apply the fair use doctrine" while Google couldn't be reached for its comment.