I am far from an expert in these matters, but as I understand it there are fair use exemptions when the purpose of the implementation is for interoperability and compatibility. Given WINE's purpose, they would seem to be on safer ground.

I believe this was one of Google's initial arguments, but as the DoJ stated when they weighed in:

>"The Android platform uses the Java programming language, but [Google] purposely designed Android not to be compatible with the Java platform or interoperable with Java programs." [1]

[1] http://www.fosspatents.com/2015/05/us-dept-of-justice-finds-...

A strange notion of 'not compatible'. I wrote a Java library in 1996 that's been used unchanged in Android apps. (Yes, the app author has to compile it to Dalvik.) [Added: it was always my understanding that this ability to use Java code was the whole point of using the Java API.]

What cases codify interoperability as a fair use exception? Wouldn't perfect interoperability have a bigger impact on the commercial value of existing products by making it easier for customers to switch to the drop-in replacement?

I think Apple would have a tough time arguing GNUstep was illegal given the wording of the OpenStep standard document NeXT and Sun produced in 1994. It was meant to be a standard.

Yes, it would seem logical to me.

What about Oracle Linux and Bash on Windows?