OHS legislation is state or territory law and there are many differences between the states and territories. The Commonwealth government, through Safe Work Australia, publishes national standards and codes to guide the states and lead to greater consistency. These standards are not mandatory but are intended to be adopted in state legislation for enforcement.
For example, a National Standard for Construction Work (NOHSC:1016 [2005]) was declared in 2005 and states are variously moving (or expected to be moving) to reflect this standard in their own legislation. (Refer section: 'Can the design be safely built' under Occupational health and safety - safe design ).