You can patent bodies, but aslong as the copies are not exact, you can get away with knocking them out.
Look at the Gibson vs ESP Explorer, obviously everyone can see that they are basically the same guitar, but slight differences in the ESP shape like the sweeping back curve make it legal.
There's loads of info on the net about Gibson trying to lawsuit just about everyone and their mothers for ripping them off.
I think it was Gibson vs PRS when they made tracings of both guitars (LP) in court, and put one on top of the other to see if it was the same shape.
