This is a huge issue with the patent world in general. There's just so much prior art out there, and you have to be really clear about showing that it applies. This isn't a patent case, but I have a great Google Maps case involving Wi-Fi where a judge completely borked it. As for this particular patent, I'm not enough of an XML expert to say whether the court got it right here. But it is worth noting that Microsoft tried to invalidate the patent several times with USPTO and failed to do so there as well. So perhaps there's something more to the patent than meets the eye, or that is was novel at that time but not modern XML. Remember, the actual i4i patent at issue was filed in 1994, and it only matters if there was prior art from before 1994. It might have been novel at the time.