I know that you can't copy the OED as a whole, or in significant parts. You have to purchase it. Similarly, you could copy and use parts of the Java API in your programs but not the whole API.

I'm not a lawyer so I don't know if Google's case is solid legally, but putting myself as a juror the Oracle opening statement I think would be very convincing compared to Google's.

But my reading of the slides is probably colored though by my personal opinion that the Java API should be copyrightable. It's a substantial creative work and no two people would create the same APIs even containing the same ideas and concepts (.NET for example).