Instead of selectively evaluating whether a jammingdevice is in the public interest (to, say, protect us from the malicious), the FCC generally blocks all such devices from the market.
The idea is to use probes similar to those used in GAARDIAN, but interconnected in such a way that the position of a jammingdevice can be determined by triangulation.
It works by jamming all nearby transmissions at the operating frequency of the medical device, except for those signals that were authorized to use the device.