A shaky business

Hand-arm vibration cases are becoming increasingly common. Judith Martin explains how a recent case highlighted the importance of date of knowledge

The case of Clark v Clark (trading as J O Clark and Sons) was heard earlier this year at Manchester County Court. It was an interesting case and highlighted several issues in relation to date of knowledge and foreseeability in hand-arm vibration syndrome cases, sometimes also referred to as vibration white finger.

The claimant was the son of the defendant - Mr J D Clark - who worked for his father for a period of 16 years from 1984 to 2000 as a farmhand. He was the only employee assisting in the operation of a large farm comprising of approximately 600 acres, together with a large sheep rearing business.

The claimant alleged he had developed HAVS as a result of working with a variety of power tools, machinery and equipment - namely power-driven sheep sheering equipment, high-pressure hoses, a chainsaw and a bruiser/crusher machine, which was used to bruise barley in preparation for feeding to animal stock. This was a most unusual case given the industry and the type of equipment used by the claimant.

Evidence at hand

Both parties obtained their own engineering evidence. Central to the case was the level of vibration transmitted. By and large, the engineers agreed that it was the chainsaw that was the most significant source of exposure to vibration, and that it was the potential source of liability. Although some of the other pieces of equipment transmitted some low-level vibration, by the time the claim was heard at trial the main allegations centred around the use of the chainsaw and the vibration transmitted.

However, the engineers disagreed on the relevance of the claimant's "occasional" and "seasonal" use of the chainsaw. The defendant's expert was of the view that this was of significance as the claimant only used the chainsaw at certain times of the year - for example, while repairing boundary fences.

The other issue for the court was the date upon which the defendant had - or should have had - knowledge of the risk of HAVS, and should have put in place systems to reduce or eliminate the risk.

As a result of several Farm Wise publications, the judge found that the defendant should have been aware of the risks of HAVS at the latest by 1992. By this date, several farming publications had been published that referred to the risk of development of HAVS and the judge found that the defendant should have been aware of the risks and have acted accordingly. The Farm Wise publication dated 1992 triggered the date of knowledge argument, and the judge gave 1993 to be the latest year by which the defendant reasonably should have foreseen vibration injury to the claimant in his use of the chainsaw.

Negligent findings

Following this date, the defendant was found to be negligent in exposing the claimant to harmful levels of vibration. The defendant's failure to take action caused the claimant to suffer permanent injury of HAVS. The judge noted that the defendant should have taken only simple precautions, which would have reduced the dose and, by inference, would have deferred and probably avoided the permanent injury suffered by the claimant.

The judge found exposure from 1984 to 1993 was non-culpable. The claimant, however, first noticed symptoms in 1997, and use of the chainsaw continued unabated until his employment ceased in 2000. The defendant was, therefore, found negligent and culpable of exposure from 1993 onwards.

As the claimant became aware of his symptoms in 1997 and because his use of the chainsaw continued from this time until 2000, the judge was satisfied that - apart from the culpable exposure to vibration from 1993 to 1997 - the claimant would not have suffered HAVS and, thus, it was this culpable use that caused the HAVS. It was held that the same period of exposure was responsible for the change from asymptomatic to symptomatic disease, and made a material contribution to the onset of symptoms and resulting disability.

In other cases - such as Allen v British Rail Engineering 2001 and Brookes v South Yorkshire Passenger Transportation Executive and Mainline Group 2005 - the judges did not apportion damages as between culpable and non-culpable exposure in the course of the relevant employment.

However, in Clark v Clark, the judge found that the culpable exposure had made a material contribution to the onset of symptoms because during that period the latent asymptomatic HAVS had converted to symptomatic HAVS.

Threshold of tolerance

The judge found that had the defendant taken the necessary precautions post-1993, the claimant's threshold of tolerance would not have been met and the claimant would not have developed HAVS.

This is an interesting case, as it illustrates the approach that the judiciary was prepared to take in considering date of knowledge in HAVS cases. Furthermore, courts are prepared to consider the type of industry and the size and resources of the operation in determining the date upon which defendants should have been aware of the risks.

The date of knowledge in HAVS cases is now a fluid issue, and each case has to be taken on its own facts. Defendants will need their own engineering evidence to deal with this issue, and they will also benefit from lay witness evidence supporting a later date of knowledge.

In Clark v Clark, the court followed the principles laid down by the Court of Appeal in Brookes v South Yorkshire PTE in refusing to discount the claimant's entitlement of damages to reflect the non-culpable exposure prior to the date of knowledge.

Furthermore, while not effecting the claimant's entitlement to damages, this may well become an issue for interested insurers, which will rightly argue that they should not contribute towards the damages for any non-culpable exposure years.

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