There's probably a grain of truth to both positions. Dealing with RF interference is something of a black art, so given that LightSquared hasn't actually deploy

There's probably a grain of truth to both positions. Dealing with RF interference is something of a black art, so given that LightSquared hasn't actually deployed their network yet, it's not surprising that existing GPS devices don't filter out those signals perfectly. At the same time, LightSquared seems to have assumed that they could avoid interfering with the GPS band to a greater degree than they were ultimately able to deliver. Of course, it's also a question of money - from the GPS manufacturers' perspective, they will have to assume all the costs while LightSquared derives the benefits. From LightSquared's perspective, they paid to acquire their spectrum while the GPS manufacturers get access to government infrastructure for free and are effectively blocking access to a significant chunk of spectrum just to reduce their per-unit costs.