t is sometimes argued—it was argued in the present case—that
making an employer criminally responsible, even when he has done all
that he could to prevent an offence, affords some additional protection to
the public because this will induce him to do more. But if he has done
all he can how can he do more? I think that what lies behind this
argument is a suspicion that magistrates too readily accept evidence that an
employer has done all he can to prevent offences. But if magistrates were
to accept as sufficient a paper scheme and perfunctory efforts to enforce
it they would not be doing their duty—that would not be " due diligence "
on the part of the employer.