[CobrastanJorji]

Indeed, an answer of "no, they're not copyrightable" would leave the world generally how it is today. An answer of "yes, all existing APIs are copyrightable" would be tremendously impactful in all sorts of ways I can't even imagine. Presumably someone would immediately sue somebody else because of a tenuous claim to ownership of, say, HTTP or some JavaScript extension.

Microsoft has filed an amibus brief for the "not copyrightable side," as has the EFF, IBM, Red Hat, and a team of 83 computer scientists.

You should probably note the folks on the "yes, copyrightable" side for future reference as well, including Dolby, the Motion Picture Alliance, SAS, the DoJ, the Recording Industry Association of America, and also 4 CS professors (Dr Spafford of Purdue, Dr. Ding of UC Davis, Dr Hollaar at Utah H, and Dr. Porter at maryland U).