[i000]

I guess that is at the core of Google vs Oracle, they copied the API kept the implementation clean-room. It was definitvely ruled that this was fair use. If fair use applies to something as strict as re-implementing an API, I would argue it applies to something much more elusive, like cloning UI/layout.

[nerdsniper]

> I would argue [fair use] applies to something much more elusive, like cloning UI/layout.

You would be very wrong in this argument. It's extremely well-established that corporate verbiage and UI are subject to copyright.