22   Offence by employee—liability of employer

(1)  If an employee contravenes any provision of this Act or the regulations, the employer is to be taken to have contravened the same provision (whether or not the employee contravened the provision without the employer’s authority or contrary to the employer’s orders or instructions).

(2)  It is a defence in proceedings against an employer for such a contravention if it is established:

(a)  that the employer had no knowledge of the contravention, and

(b)  that the employer could not, by the exercise of due diligence, have prevented the contravention.

(3)  An employer may be proceeded against and convicted under a provision pursuant to subsection (1) whether or not the employee has been proceeded against or convicted under that provision.