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Oracle is appealing last year's ruling that Google's use of Java APIs in Android constituted "fair use".

Oracle vowed to appeal Google's win last May and on Friday filed that action at the US Court of Appeals for the Federal Circuit, which in 2014 ruled that APIs can be copyrighted.

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Google last year convinced a district court jury that its use of 37 Java APIs met fair-use conditions, allowing it to dodge Oracle's $9bn claim.

Oracle now argues it's entitled to a new trial because the district court "repeatedly undermined Oracle's case", leading the jury to make the wrong decision. For example, it says the court wrongly bought Google's claim that Android was limited to smartphones while Java was for PCs, whereas Oracle contends that Java and Android both compete as platforms for smart TVs, cars, and wearables.

"The district court barred all evidence of Google's competition in any market other than smartphones and tablets," write Oracle's lawyers.

"This evidence would have eviscerated Google's theory of 'transformative' use, the core of its fair-use defense," they argue.

Oracle is accusing Google of "classic unfair use", where a "plagiarist takes the most recognizable portions of a novel and adapts them into a film".

"Google copied thousands of lines of copyrighted code from Oracle's Java programming platform. Google concedes it put that code to the same use in the competing Android platform, for what this Court already has deemed 'entirely commercial' purposes. And Google reaped billions of dollars while leaving Oracle's Java business in tatters," Oracle's lawyers say in the brief obtained by The Register.

Oracle's bid for a new trial at the US District Court for the Northern District of California was knocked back in September. Oracle said it deserved a new trial because Google "completely concealed the ARC++ project" to bring Android apps to Chrome OS hardware.

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