A jury in a high-profile technology case has ruled that Google violated copyrights owned by Oracle for the Android mobile platform, but failed to agree on whether damages should be awarded.
In a partial verdict, jurors were unable to decide on a key point of whether Google's use of copyrighted Java software was "fair use" that made it acceptable.
The verdict prevents any potential for an Oracle windfall, but the case between the two tech titans now moves to another phase on whether Oracle's patents were violated.
"There has been zero finding of liability on any copyright so far," US District Court Judge William Alsup told the rival lawyers after the jury left his San Francisco courtroom.
"The affirmative defence of fair use is still in play."
The jury, which had been struggling to reach a unanimous decision, concluded that Google infringed on the copyrighted programming language for a portion of Java known as RangeCheck. But it also agreed that Google demonstrated that it was led to believe it did not need a licence for using Java.
Oracle said it was pleased with the verdict.
"Oracle, the nine million Java developers and the entire Java community thank the jury for their verdict in this phase of the case," a company statement said.
"Every major commercial enterprise -- except Google -- has a licence for Java and maintains compatibility to run across all computing platforms."
Oracle lawyers who originally said they would accept whatever damages were dictated by the law regarding that portion of the case switched position and asked for jurors to determine the monetary compensation.
Alsup said, however, that "it borders on the ridiculous to say that with nine lines of code you are going to even get a percentage as damages," in an Android platform with 15 million lines of code.
Oracle accused Google of infringing on Java computer programming language patents and copyrights Oracle obtained when it bought Java inventor Sun Microsystems in a $US7.4 billion ($A7.31 billion) deal in 2009.
Google has denied the claims and said it believes mobile phone makers and other users of its open-source Android operating system are entitled to use the Java technology in dispute.
The trial is being conducted in separate phases to address copyright and then patent infringement accusations by Oracle.
The internet titan unveiled the free Android operating system two years before Oracle bought Sun.
Oracle's challenge of Google in court over copyrights was an unusual tactic that being watched intently in Silicon Valley.
In the fast-paced land of internet innovation, it has been common for software writers to put their own spins on application programming interfaces that mini-programs use to "talk" to one another.
A Google statement said: "We appreciate the jury's efforts, and know that fair use and infringement are two sides of the same coin. The core issue is whether the APIs here are copyrightable, and that's for the court to decide. We expect to prevail on this issue and Oracle's other claims".
Alsup called the jury back into the courtroom to start a second phase of the trial devoted to whether Google violated Java patents.
Jurors were shown video explaining patents. While copyright applies to written works such as songs, a patent was described as being on par with a property deed issued to inventors giving them rights to defend creations.
Oracle lawyer Michael Jacobs said fair use is not a defence in patent infringement. He said the company will show Google improperly used the Java patents which speed up the processing for computers or mobile devices.
"These patents are about making phones run fast," he told the jurors.
Google is due to present its statement to the jury on Tuesday. Part of the Google defence is that Oracle couldn't figure out a way into the smart phone market and is thus trying to leech off of Android's success by pressing claims regarding Java software that Sun made publicly available.