Most jammers work by blasting noise on whatever channels you are trying to block.
Perfect band pass filters are not a thing the exist, especially not for transmitters. Especially not for transmitters cobbled together by some guy on the cheap. The assumption that they do is why they (rightfully) smacked down LightSquared.
So, let's do a little exercise:
First, look at the 800 MHz Band Plan
http://www.fcc.gov/encyclopedi...
See that slot right below "Cellular?" You know, that cut-away that has all the "Public Safety" allocations? Now, let's look at a quote from the FCC posting:
"According to deputies from the Sheriff’s Office, communications with police dispatch were interrupted as they approached Mr. Humphreys’ vehicle."
The jammer was blocking police radio. Not just cell phones. He was actively interfering with public safety communications. NON-CELLULAR public safety communications.
Personally? $48,000 is getting off easy. I'd add another order of magnitude onto it.