You would hope people are conversant with these laws;
CIVIL AVIATION SAFETY REGULATIONS 1998 - REG 67.270
Offence--doing act while efficiency impaired
(1) This regulation applies in relation to a
licence of any of the following kinds:
(a) flight crew
licence;
(b) special pilot
licence;
(c) flight radiotelephone
licence;
(d) air traffic controller
licence.
(2) The holder of the licence must not do an act authorised by the licence if at the time:
(a) he or she knows that he or she has a
medically significant condition; and
(b) the condition has the result that his or her ability to do the act is impaired.
Penalty: 50 penalty units.
In other words you can technically be convicted and fined if in breach. Try maintaining your ASIC with a conviction against your name. If you are not fit for duty you shouldn't be crewing an aircraft and based on recent occurrences the CASA definition of medically significant condition is very much 'no matter how minor'.