The HSE Act does not prescribe exactly what steps employers are required to take in order to comply with their obligations.

But a case in which Duncan Cotterill was involved clarifies the health and safety obligations of principals and head contractors and is relevant to all contracting companies who engage contractors or subcontractors.

The case concerned a construction company which was prosecuted by the Department of Labour over an accident caused by the negligence of one of its subcontractors. The judge dismissed the charge against the construction company as head contractor for failing to adequately monitor its subcontractor. The subcontractor had been convicted and fined earlier, having entered a guilty plea.

Duncan Cotterill's Health & Safety team defended the head contractor in this case.

The decision will also have implications for project management offices (PMOs) involved in the Christchurch rebuild as recent cases indicate that the Ministry of Businesss, Innovation and Employment (formerly the Department of Labour) intends to apply duties owed by principals (and head contractors) to project managers.

In the case, a construction company was engaged as head contractor to replace two railway bridges for the client. It subcontracted a piling specialist to help with a variety of tasks including building two temporary platforms from which work would be done on the main bridge. The piles on the second temporary platform were inadequate, causing the platform to collapse and the crane on it to topple and fall into the water. Fortunately, no-one was injured.

The evidence was clear that the platform failed because the piling methodology used by the subcontractor was inadequate.

The Court found that a principal or head contractor is clearly responsible for having overall control and management of the construction project, for monitoring health and safety issues and having a clear policy in place.

But the head contractor is not required to oversee the technical aspects of the work that it has contracted out, particularly if it has no expertise in that work, and those matters are within the role and expertise of the subcontractor.

The construction company was found not to have breached the Health and Safety in Employment Act 1992 and accordingly the charge against it was dismissed.

The decision confirms that the head contractor is responsible for checking the competence of subcontractors it engages and, once the project starts, for general safety onsite, but its obligations do not extend to "insuring" the subcontractor's workmanship. Where a subcontractor is negligent, responsibility for that safety issue must lie with the subcontractor itself.

The Court agreed that while the head contractor will not necessarily need to be onsite at all times, they must regularly communicate with their subcontractors and have adequate site contact to be able to effectively monitor health and safety aspects.

MBIE has appealed the decision and the High Court will hear the appeal in April 2013.

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