38 The submissions of the parties pertaining to the costs, difficulty and trouble necessary to avert the risk centred around two proposals: first, the possibility of a full-time employee manning the gate; and secondly, additional warning signs or barriers. St Hilliers submitted that the only way to secure the gate was to have a person manning the gate permanently over the years of work at the site at an estimated annual cost of approximately $50,000, which would be "completely disproportionate" given the unlikelihood of the risk. There was no evidence concerning the derivation of this figure, or any other aspect of this proposal.
39 St Hilliers did not attempt to suggest that it would not have been reasonably practicable to put in place some additional form of barrier or warning sign and indeed Mr Hughes gave the following evidence: that once the portal was re-erected after the incident, St Hilliers "barricaded the area with some bunting"; "bunting is a hazard warning, probably more than a tape 3 foot wide, 100mm, bright colour"; and "it can have a purpose as a hazard warning". Rather, St Hilliers submitted that a locked gate should have been sufficient; according to St Hilliers, if someone was prepared to cut a lock, it is unlikely that a simple barrier or flag would stop them. Alternatively, WorkCover suggested that St Hilliers could have used bollards to prevent access through the gate, which would have been neither expensive nor impracticable. However, WorkCover did not expand on how this would have thwarted a person's efforts to cut the fence ties to gain access to the site or as to other measures of practicability.
40 We find that it was not reasonably practicable to take additional measures to guard against someone unlawfully gaining access to the gate. In this regard, we consider that this case falls into the category such as Cleary Bros, where there is an absence of an affirmative case by the prosecutor counteracting the defendant's submissions to demonstrate that some other measures were available that were reasonably practicable for St Hilliers to adopt and that would have addressed the risk of unlawful access to the site.
41 We next consider s28(a) in the context of the second particularised failure - the failure of St Hilliers to inform Mr Openshaw not to use the entrance. This raises quite distinct issues from whether St Hilliers could have done more to thwart someone cutting the fence ties to gain access to the site. There are several important points to make at the outset of this discussion. First, notwithstanding the submissions on the part of St Hilliers that it did inform its subcontractors, De Martini and Gasparini, the week before the incident that the Stevens Road gate was closed, there was nothing in its amended application for leave to appeal and appeal to suggest that it intended to challenge his Honour's findings concerning liability on the ground that this failure had not been established to the requisite standard of proof. Secondly, we are satisfied (in conformity with his Honour's decision) that the failure was established beyond reasonable doubt. Accordingly, it is necessary to consider whether a defence under s28(a) is also available in respect of the second particularised failure. Our earlier finding that it was not reasonably foreseeable that someone would cut the fence ties does not address this question as it raises a quite distinct issue relating to whether St Hilliers' communications to Mr Openshaw not to use the gate were sufficient.
42 We do not accept St Hilliers' contention that a locked gate was sufficient communication to Mr Openshaw not to use the gate, particularly in circumstances where his delivery docket expressly directed him to use the gate; where the other entrance was impassable; where the locked gate had been breached; and in view of Mr Openshaw's previous experience with access through the Stevens Road gate (including that he had used it on a number of occasions and that the gate had always been open when he was to use that gate). Thirdly, St Hilliers' submissions concerning impracticability in relation to this particular amounted to nothing more than a contention that the risk was not reasonably foreseeable and a contention that it was impracticable to inform Mr Openshaw because St Hilliers never knew which drivers would be allocated to deliver concrete on any particular day.
43 We have already canvassed the nature, likelihood and gravity of the risk to safety occasioning the offence. Against that, in the context of this particular, must be weighed the costs, difficulty and trouble necessary to inform Mr Openshaw not to use the Stevens Road entrance; for we have no doubt that, on the evidence, had Mr Openshaw been so informed directly or through Boral, he would not have used the entrance. In our view, it is not possible to sustain an argument that it was not reasonably practicable to inform Mr Openshaw not to use the entrance, particularly in light of the gravity of the potential consequences and the fact that the concrete portal had just been completed and represented a distinct change to the situation that the concrete suppliers would have been familiar with. A written direction to De Martini and Gasparini that all concrete suppliers used by it must henceforth use the McPherson St entrance would have been sufficient, in the light of the persuasive evidence of Mr Ryan, who controlled batch allocations for Boral. Mr Ryan stated in evidence that if he had been told that the Stevens gate entrance was no longer to be used he would have changed the details on the delivery dockets; he'd always been "pretty spot on in his dealings and I can't believe I would have left it on there".
44 In conclusion, given the gravity of the potential consequences, the fact that the portal presented as a newly changed circumstance and despite the fact that the risk of unlawful access by cutting the fence ties was not reasonably foreseeable, we do not consider that St Hilliers has established, on the balance of probabilities, that it was not reasonably practicable to inform Mr Openshaw not to use the Stevens Road entrance. Accordingly, we do not consider that a defence under s28(a) of the Act is available in respect of the second particularised failure. We are satisfied that it was reasonably practicable for St Hilliers to have done more to have inform Mr Openshaw not to use the Stevens Road gate and of the new circumstances at that entrance.
Section 28(b)
45 Section 28(b) provides that:
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:
(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 to make provision.
46 St Hilliers drew the following distinctions between ss28(a) and (b): first, St Hilliers contended that unlike s28(a), s28(b) does not speak of risk, or compliance with the provisions of the Act; it looks at the causes of the commission of the offence. Secondly, St Hilliers noted that s28(a) speaks about reasonable practicability, but (b) speaks about impracticability with no qualification of reasonableness which suggests there is an important difference. While we agree with the second observation, for the reasons we shall give, the first distinction is a distinction without substance given the proper interpretation of the phrase "commission of the offence".
47 St Hilliers submitted that his Honour failed to properly consider the availability of the statutory defence under s28(b) of the Act and we have already found that the magistrate did not give proper consideration to St Hilliers' submissions. As to the availability of the defence, St Hilliers submitted that:
(a) the commission of the offence was due to a cause over which his Honour found St Hilliers had no control (the gate being cut) and that if the gate had not been cut, there would have been no detriment to health and safety. No other back-up measures were necessary; closure of the gate completely obviated the risk;
(b) it had no control over whether the carpet layers cut open the Stevens Road gate. Nor did it have any control over another causative factor: the fact that Mr Openshaw did not keep a proper lookout;
(c) the statutory requirement for the employer to show the impracticability of making provision in s28(b) relates to the causative facts which are contained within the meaning of "commission of the offence": McMartin v BHP (1988) 100 IR 241 at 246;