bilbert,
Parliament Legislates, that is, makes Legislature, the law.
CASA Regulates those laws, that is, the Regulator!
CASA does write regulations, they are then passed to the Parliment, voted on and become law. CASA then regulates and inforces the "Law". Exactly like most other government departments.
Quite simple really! Except now they are unable to Regulate, because the Federal Court Knows best!
Interesting that AT can operate with Training and Checking Restrictions, but they still do not have a Chief Pilot!