Oracle and Google have locked horns again over a Java programming language copyright case and they are back battling it out in the courtroom.

Google-owned Android operating system is one of the most popular smartphone platforms in the world. Sun Microsystems created Java programming language and Oracle acquired the company in 2010. Oracle sued Google in 2010 and claimed that it had incorporated some aspects of Java in its Android platform without Oracle's permission.

Google claims that Oracle is not entitled to have copyright protection over certain aspects of the Java programming language. The case filed by Oracle against Google is also examining if the computer language, which connects programs (more commonly known as application programming interfaces or APIs) can be copyrighted.

Oracle originally claimed more than $6 billion in damages, but the judge cut that down and now Oracle is seeking $1 billion as copyright claims.

Oracle does not dispute that Google developed the original code for Android. However, Oracles claims that Google used 37 Java APIs to develop Android operating system, which is enough to violate its copyrights. However, U.S. District Judge William Alsup said that the Java APIs used by Google in Android were not subject to copyright protection by Oracle and is free to use by all.

"So long as the specific code used to implement a method is different, anyone is free under the Copyright Act to write his or her own code to carry out exactly the same function or specification of any methods used in the Java API," said Alsup.

The battle between the two tech giants in San Francisco has already attracted a lot of attention. After a heated hearing on Wednesday, December 4, Alsup deferred his legal ruling until after a jury had heard substantial evidence on other issues of the case.

Oracle attorney Joshua Rosenkranz has asked the appeals court to rule that Java APIs were subject to copyright, and that Google was not entitled to a fair use defense.

Google attorney Robert Van Nest said that if the Federal Circuit decides that copyright applies to the APIs, they would pursue a second jury to consider fair use of APIs.