The new CASR parts (replaces CAR 1988) coming in 2005 will deal with "transport related offences".
This sort of replaces the "fit and Proper person" which was vague to say the least.
If you have a repeat history of transport related offences (road, rail, water craft) then it shows a disregard for safety and you may not be able to hold a flight crew licence under the regulations.
New checks are also being done by ASIO, AFP and DIMIA, so there are more ways to keep people out of the system.
I believe in USA they take it a step further and if you lose your motor vehicle licence or get a DUI, you automatically lose your pilot certificate for the corresponding period.