What determines that approach? The way judge decides to do it in each case?
In this case however the biggest damage is that they reversed the ruling that APIs aren't copyrightable. Is there any way that Google can reappeal it in a higher court, or it's a final decision? In Europe APIs were ruled uncopyrightable some time ago, but somehow this didn't help in this case.
Google could request rehearing en-banc (IE in front of the whole federal circuit).
If that succeeded, the decision would be vacated until the en-banc rehearing.
Whether that happens or not, they can also appeal it to the supreme court.
Suffice to say, my completely personal view is that it was appealed to this very court for a reason. Normally, this is the court that hears all patent appeals. Because the original lawsuit involved patent claims, they have jurisdiction, even though there are no patent claims being appealed.
Otherwise, it would have gone to the 9th circuit, who, i suspect, would have been more favorable.
> What determines that approach? The way judge decides to do it in each case?
A fair use defense means that something happened that would otherwise create liability, but doesn't because of some (often policy) reason. Making something an affirmative defense has procedural implications. But "rights" can be implemented as affirmative defenses. For example, truth is an affirmative defense to defamation in the U.S., even though it's closely connected with free speech rights.
EDIT: But see dragonwriter's very pertinent comment about defamation cases involving matters of public concern, where falsity is an element of the claim rather than an affirmative defense.
The practical distinction is that it's easier to dispose of cases on a motion to dismiss when something is a required element of the claim versus when it is an affirmative defense.
> For example, truth is an affirmative defense to defamation in the U.S., even though it's closely connected with free speech rights.
This is wrong, at least on matters of public concern, specifically because it is connected to free speech rights, both for public figures and private figures as plaintiffs, who bear the burden of showing falsity rather than the defendant having the burden of showing truth.
See Philadelphia Newspapers v. Hepps, 475 U.S. 767 (1986); New York Times v. Sullivan, 376 U. S. 254 (1964).
It's more proper to view it as a right.