It's not circular reasoning. The flow is clear: the Constitution gives Congress the power to make copyright law, Congress passed laws doing so, and the courts work out the details at the margins for stuff Congress didn't make explicit. Software is very much explicitly mentioned by the copyright laws that have been passed by Congress, so there's no reasonable doubt about the legal foundation there. API copyright isn't explicitly supported by statutory law, so for the courts to affirm API copyright on their own, they need to provide a convincing derivation of its existence as implicitly covered by existing statute. I doubt they can do so, and they obviously cannot do so without overturning a lot of previous precedent.

And all of the above is about the legal, technical questions about what the law is. The public policy question of what the law should be is a different matter entirely, and opinions about that generally should be addressed to Congress, not the Supreme Court.

APIs are functional, not artistic. They belong in the domain of patent law, not copyright.

> APIs are functional, not artistic. They belong in the domain of patent law, not copyright.

I think you're mixing up different types of intellectual property:

- Trademarks are intended to identify a source. Trademarks cannot be functional, they have to be descriptive.

- Copyright must express a creative idea. That idea can be artistic, or functional. Computer code and APIs can be copyrighted (as they most often are), but they can also be patented.

- Patents cover inventions with some utility. One can definitely patent a piece of art if it provides some utility.

It's not uncommon for companies to throw all three at whatever they are cooking up.

Copyright does not only cover artistic works. APIs are a form of contracts and contracts are copyrightable.

APIs aren't a type of contract in the legal sense.