They did not say that APIs were copyrightable, they said that if "we assume, for argument's sake, that [APIs are] copyrightable, [...] the copying here at issue nonetheless constituted a fair use".
From page 1 of the opinion, i.e. the actual ruling, which follows the "syllabus" in the pdf. The syllabus is basically just a summary. It's page 5 of the pdf.
I see; the difference is SCOTUS vs. circuit court of appeals precedent. I was referring to the decision of May 9, 2014 that overrulled the Alsup court assertion that APIs are not subject to copyright. But that decision was not from SCOTUS but from the appeals court for the circuit.
Current status, if I understand correctly, is that SCOTUS has not weighed in on whether APIs may be subject to copyright, and precedent in (Edit: Ninth Circuit) should be that they are to be considered copyrightable (and, I suppose, "no precedent in this circuit or from the Supreme Court" in all other circuits).
I don't think federal circuit rulings on non patent matter are binding precedent anywhere? I could be wrong about that. I certainly doubt there binding precedent on just one federal district (and not either all the district courts in the relevant circuit, or all district courts period).
From page 1 of the opinion, i.e. the actual ruling, which follows the "syllabus" in the pdf. The syllabus is basically just a summary. It's page 5 of the pdf.