This one time (at band camp) when I was getting a canary off, the inspector told me that the cops don't have any formal mechanical training, and very few have any ADR training.
The law provides that they if they have reason to believe that there is an unsafe modification/component on a vehicle it provides grounds for a defect notice.
As stated previously, I have a mod permit for everything on my car but they can say what they want and ignore the permit because they have "grounds" to believe that a defect exists.
A mate got done for a dusty indicator globe. Yep, no shit. When he got pulled over, we were in the back seat doing the "disco pig" to the flashing lights at night and the cop didn't like it one bit. It was in an immaculately restored EH.
I've been done for a BOV when I had an OEM bypass valve, car being too low when its was 120mm high, having a VeilSide decal over the windscreen when it was no less than 10% of the height of the windscreen and outside of the wiper arc, having an aftermarket aluminium radiator, the list goes on.
Most of us here know more about ADR's than the cops because we deal with the inspectors on a regular basis because of the inept abilities of the police at performing what is supposed to be part of their job criteria. If they have no idea what they are looking at, they should have an ADR book to provide an answer to the question that they are seeking, not just slap a lickie on someone's windscreen because they have "reasonable grounds".
I have used one inspector each time I get labelled and they guy knows my car like the back of his hand. The problem is the cost of the inspection and the time wasted to get something off that clearly shouldn't have been placed on by some dickhead who wouldn't know the difference between a pile of shit and his own mother's hair do.
Unfortunately, there's nothing we can do about it as the media hype against hoons has tarnished our existence on public roads. Granted, some peanuts have inflated this issue by causing problems in residential areas, but the majority of us are generally well behaved members of the public who are true car enthusiasts.
There have been many police corruption cases evident in the past, but what would the police think if the public initiated a campaign to tar every police officer with the same brush?
The police have too many powers at their discretion and that's the real issue here. They need formal training to identify real ADR infractions before handing out legal harassment notices.