IBM hasn't been doing that for decades, despite the supreme court decision being quite recent - I think that was more about clean room reimplementation than APIs.

My point wasn't about ruling differently but the lack of rulings/laws making it explicitly legal creating uncertainty and opportunities for Oracle/Apple to go after people. Some countries have other ways to deal with it too, e.g. NZ allows reverse engineering for compatibility purposes, which seems likely to cover APIs (not sure, haven't needed to know).