33. Subject to article 32(11), in any proceedings for an offence under this Order, except for a failure to comply with articles 8(1)(a) or 12, it is a defence for the person charged to prove that he took all reasonable precautions and exercised all due diligence to avoid the commission of such an offence.
What the Guidance says:
Article 33 provides a defendant with a defence of due diligence, ie – it is open to the
person charged with an offence under the Order to prove he took all reasonable
precautions and exercised all due diligence to avoid the commission of such an offence.
The defence of due diligence does not, however, apply where the responsible person
is alleged to have failed to have taken such general fire precautions as will ensure
the safety of his employees, or to have failed to eliminate or reduce the risk from
a dangerous substance present on the premises. Nor does the defence apply to an
employer where failure to comply with the provisions of the Order is due to an act or
default of his employees or appointed competent persons.