For once CASA is on the front foot. If you can't handle that, then get out of the cockpit or workshop or ATC unit, etc!
CASA should not have to rely on a history of Drug and Alcohol related accidents and/or incidents to decide to be pro-actively trying to avoid accidents and/or incidents that have a connection to misues of Drugs and/or Alcohol.
The sad reality is that many people regardless of their social, economic, or ethnic, etc background, do misuse Drugs and/or Alcohol. The aviation community is not immune to such misuse BUT, importanatly, the aviation community manages a high risk mode of transport that cannot afford even minor transgressions. That CASA is attempting to identify transgressions known to be capable of causing unacceptable risk exposure to the flying public (which includes me) gives me a great deal of comfort.
Off-duty or not, you should not be an impediment to CASA officers lawfully conducting their duty. If 3RAR bothered to read the regulations related to drugs and/or alcohol impairment, you would realise that provided you are not contributing to the aviation service for which you are trained (other regulations relate to how you may interfere with an aviation service when neither trained nor on duty), you need not fear prosecution.
Some of the posts on pPrune here and elsewhere, indicate to me that I have had a misperception that all aviation employees are professionals. Clearly, some are not and some (even more disturbingly) lack simple (let alone the required complex) intelligence.
ID