It is a defence to any proceedings against a person for an offence against a provision of this Act or the regulations if the person proves that:(a) it was not reasonably practicable for the person to comply with the provision, or(b) the commission of the offence was due to causes over which the person had no control and against the happening of which it was impracticable for the person to make provision.
Coal Mine Health and Safety Act 2002 No 129