Shagpile, ADS-B is line-of-sight RF stuff. not satellite. It's aimed at national coverage above F280. Aside from low level flying what rules are you concerned about that altitude, speed or position information alone would cause you any grief with CASA?
Sunfish, CASA could just subscribe to something like flightradar24 if they wanted to find out where a particular aircraft was. Fit out the detector van with an ADS-B receiver and drive to the location for a more detailed look. No idea on the admissibility as evidence. ADS-B might make it easier for CASA to find an aircraft but is hardly going to convict you. You have to cooperate and turn it on in the first place.