Anyone using fork(), stat(), open(), or other basic parts of the UNIX development environment would be in violation.
Those copyrights were purchased by Novell at some point, and I believe ended up with Attachmate.
One would think that the C Programming Language is also covered by copyright via the K&R books, which would put anyone using printf() in the same position.
That is truly a nightmare scenario.
Absolutely, but courts are supposed to interpret the law, not rule whichever way avoids nightmare scenarios.
The risk of going too far in that direction (and this is by no means the first case in which SCOTUS c̶l̶e̶a̶r̶l̶y̶ may have rationalized a decision for pragmatic reasons) is that it makes the court more corruptible. I am glad the majority ruled this way, because I agree that it leads to a better outcome in this case. On the other hand, any departure from a pure interpretation of the law is very dangerous, because it normalizes the more-corruptible mode of operation, and that can lead to another kind of "nightmare scenario".
You should read the law in question. This would be Section 107 of the Copyright Act, which defines "fair use". It's extremely vague and is best interpreted as a set of considerations that the courts should take into account so that they can handle situations like this one on a case by case basis. If Congress wanted to be more prescriptive, they could (ETA: and if they become unhappy with the courts' decisions they still can in the future), but I think that would lead to worse outcomes.
I was really just responding to the implication that SCOTUS did the right thing because "it would be a nightmare scenario" otherwise.
The law also states that copyright's purpose is to stimulate progress of the arts, and that's why fair use is possible. Interpreting the law also means establishing the limits of fair use.
But, still, yes, determining the scope and applicability of fair use is part of applying the law.
That would seem a reasonable outcome, for much the same reason that copyright not protecting the appearance of fonts under US law is reasonable. Yes, it is overriding copyright protection for a creative work that would otherwise apply. However, it does so because a greater good is served, in this case by ensuring that interoperability cannot be encumbered, something which (as the majority opinion alludes) goes against the very purpose of copyright under US law.
One could argue that this is for the judicial branch, not the legislative branch, to decide.
Now, how do you let third parties program against that non-public API? Would only showing it to licensees be a legal way to do that?
If so, and if the API becomes popular, I don’t see how to prevent those licensees from leaking the API to the world, say through small code snippets on Stack Overflow.
One thing I do see happening is that sensitive and expensive to develop algorithm internals may be prevented from leaking into APIs. I, again, don’t see this as anything other than a win for devs. An API is fundamentally used to get stuff done, if a developer doesn’t need to know the implementation details I overall think this is a win for the developer using the API.
Ironically the most protected APIs may be the ones nobody implements.