There is no percentage below which copying is fair use, and it certainly isn't 10%—if it were, Oracle would have had no case, since the interface code Google copied was under 1% of the Java code.
Fair use depends on four factors. One of them is how much was copied, but there's no bright line; courts have to decide subjectively. The others are: the purpose and character of the new work (some purposes are special, like education; and, if the character of the new work is different enough from the original, it's considered transformative, which is a help); the nature of the original work (the more creative, the more protection); and whether the new work diminishes the market for the original.
In this case, the Court decided that the amount of copying was tiny, Android was substantially different from Java 2 Standard Edition, the API that was copied was more functional than creative, and Android didn't interfere with the market for Java. (This last seems odd: Sun did have a version of Java for cellphones, Java 2 Micro Edition, and it was possible to buy J2ME apps, until the rise of Android and the iPhone killed it off. I gather the Court decided that wasn't substantial, maybe because J2ME was never a large part of the Java market.)
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Not 10%
Date: 2021-04-09 12:35 am (UTC)Fair use depends on four factors. One of them is how much was copied, but there's no bright line; courts have to decide subjectively. The others are: the purpose and character of the new work (some purposes are special, like education; and, if the character of the new work is different enough from the original, it's considered transformative, which is a help); the nature of the original work (the more creative, the more protection); and whether the new work diminishes the market for the original.
In this case, the Court decided that the amount of copying was tiny, Android was substantially different from Java 2 Standard Edition, the API that was copied was more functional than creative, and Android didn't interfere with the market for Java. (This last seems odd: Sun did have a version of Java for cellphones, Java 2 Micro Edition, and it was possible to buy J2ME apps, until the rise of Android and the iPhone killed it off. I gather the Court decided that wasn't substantial, maybe because J2ME was never a large part of the Java market.)