> 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.