Lightsquared's signal is not bleeding into others spectrum. The GPS industry is in Lightsquared's spectrum and is paying tons of money lobbying so they don't have to fix it. Lightsquared may not be using the spectrum as it was initially intended, but it is staying within it's own spectrum which would not interfere with GPS if they stayed in theirs. That is the argument.
And the argument is invalid, since that absolutely isn't true. The GPS industry is NOT in LS's spectrum. It's that LS is operating on their spectrum at a power level several orders of magnitude higher than what they're licensed for. If they choose to use the spectrum as licensed, there will be no problem.
You're right - research is key. You should really do some. -- The goal of the broadcast engineer is to get all the meters on the transmitter to go as far to the right as possible!!