Immediate reason for not giving up documents: Google is worried about leaks involving their search algorithms, which are very closely guarded (and for good reason - it's been their bread & butter up to now.)
This is going to be interesting to watch, as the 'States might successfully argue that to properly understand if anticompetitive behavior took place, they need to open up the hood to the car, so to speak, and take a look at what's underneath...
