It's an active attack (requires you to transmit traffic to trick the radio into sending the response beacons) so at the very least you'd almost certainly be in

It's an active attack (requires you to transmit traffic to trick the radio into sending the response beacons) so at the very least you'd almost certainly be in violation of some FCC regs. So the charge might not be "tracking law enforcement" but rather would be "illegally transmitting on a public safety frequency without a license" or something along those lines. And if somebody got caught doing this, I'm reasonably sure they'd find a way to pile on a few more charges as well. And note that since it is an active attack that requires the attacker to transmit, it opens up the possibility of the attacker giving up their own location in turn. My take is that it's fun to think about, but largely lacking in real world applicability in most situations.