it is hard, but not impossible, to prove that you did not infringe controlled airspace, when the radar say otherwise.
That may have been the case pre-GPS but no longer. The GPS log will soon reveal whether or not you stuffed up and I doubt you would have any trouble getting it to stand up in court.
The biggest problem with CASA is that they hide behind the "administrative" fine caper.
"Sir, you can be gaoled for 8 years and fined $40k for your crimes - but if you pay an administrative fine of $500 we will call it all square"!
Dr 