While the result is a big relief, I think it's not as decisive as I'm noticing some headlines (and commenters) are claiming. One of the big open questions is "are APIs copyrightable?" The court skirted that question, and instead focused on whether it was fair use: > To decide no more than is necessary to resolve this case, the Court assumes for argument’s sake that the copied lines can be copyrighted, and focuses on…
Thomas's dissent explicitly points this out. Without diving into "are APIs copyrightable?", the majority are skipping what should have been evaluated first before saying if they were fair-use or not.
Which is obviously false. A fair use analysis can -only- take place if the assumption is the code is copyrightable; if the majority had first decided the code was not copyrightable, fair use is immaterial.
Thomas' argument, if followed, would either have led to this same decision, or would make the opposite point he was trying to make.