Tree risk management and the law: a quick guide
Last winter we saw a number of high profile cases of catastrophic tree collapse resulting in deaths and injuries. Despite their severity, such cases are rare and for that very reason they become newsworthy. Gabriel Fay provides a quick guide to the liabilities of and duties owed by public sector bodies managing a diverse portfolio of trees and woodland.
Placing hazard and risk into context, a hazard is anything with the potential to cause harm while the risk is the likelihood of that harm occurring. Therefore, every tree poses a hazard of some kind but each hazard poses a different level of risk. The number of deaths caused by falling trees or branches in the decade from 1999 until 2009 was 64. This equates to a risk factor to the population as a whole of approximately 1 in 10,000,000, an average of 6.4 deaths per annum. Contrast this with the 1754 deaths caused by road traffic accidents in 2012 alone.
Trees by their very nature are likely to cause significant damage and/or injury should they fall in whole or in part when in close proximity to people or property. However, given that the likelihood of such collapse is small, providing a local authority can demonstrate an appropriate system of inspection of its tree stock, claims arising from such collapses are eminently defendable.
The utility of trees cannot be understated. They are aesthetically pleasing, have been shown to have a positive impact on both physical and mental health, promote bio-diversity and provide a bond between present society and the past. These are more than simply lofty notions in respect of our surrounding environment and these considerations have clearly filtered into judicial decision making in determining liability in respect of catastrophic tree collapse.
This article will be predominantly limited to considerations of civil liability in respect of tree failure. The duty on local authorities pertaining to their trees can be found in both statute and at common law.
Highways Act 1980
Highway Authorities have a power under Section 154 Highways Act 1980 to require or carry out remedial works should trees or vegetation on land abutting a highway be considered to obstruct or endanger users of that highway. However, this is a power and not a duty. The distinction was considered in Stovin v. Wise  CA where it was held that the Highway Authority was not liable to the claimant injured by a tree on land adjoining the highway by failing to exercise its discretionary power.
Under Section 41 the Highway Authority has a duty to maintain the highway. It is open to debate whether s.41 applies to those trees that line the highway and are under the control of the Highway Authority. In Chapman v. Barking & Dagenham  the claimant suffered catastrophic injuries when a tree collapsed hitting his van. That claim was brought against the council under both common law negligence and under s.41. On appeal the case was found in favour of the claimant but at both first instance and appeal the court circumvented the issue of whether s.41 applied and the question has not been determined since.
Assuming that such a duty does arise under s.41 then the statutory defence under Section 58 to prove “that an authority had taken such care as in all the circumstances was reasonably required to secure that part of the highway to which the action relates was not dangerous for traffic” will apply.
Case law pertaining to liability in respect of trees tends to be argued in negligence, nuisance or under the Occupiers’ Liability Acts 1957 and 1984. In essence the claimant seeks to prove a duty that the defendant owes to him/her; that the defendant has breached that duty; and that the breach has caused damage to the claimant.
It is accepted that the owner of land on which trees stand owes a duty of care to those people who might be affected by those trees. The duty is to take such care as is reasonable in the circumstances for the safety of those who come within the target area of a tree.
In Caminer v North London Investment Trust  the Court of Appeal held the standard of care to be that of a reasonable and prudent landowner. This clearly begs the question as to who this landowner is and what degree of knowledge should s/he be endowed as having? In this case, it was thought that some degree of knowledge of trees would be expected but this would fall short of that of an arboriculturist.
From the authorities, the level of knowledge that should be possessed by a reasonable landowner in fulfilling its duty of care the inspection of its tree stock will be assessed by the court on consideration of the extent of tree stock, the use of the land and the resources available to the landowner.
Liability tends to be determined on the following considerations:
How remote was the tree from both people and property (target area)?
Would the defect in the tree have been identifiable by reasonable inspection?
Was there any inspection regime in place?
Was the inspection carried out competently?
The location of the tree is pertinent to whether harm being caused by its collapse is foreseeable. If the tree is in the middle of a wood where no one visits it can hardly be said to be foreseeable that someone would be injured should that tree collapse. Indeed this was implicitly referred to in Caminer, Per Lord Radcliffe: ‘
…The accepted test that liability only begins when there is apparent in the tree a sign of danger has the advantage that it seems to ignore, or to a large extent to ignore, the distinction between the spot that is much, and the spot that is little, frequented…’
This must then feed into the any risk management strategy for Local Authorities. Determination of the location of the Authority’s tree stock will be vital in assessing which of those trees require close and frequent inspections. This is generally known as “zoning” so that trees located in areas of high use (such as roads, car parks and schools) take priority over those situated in less frequented areas.
In Bowen v National Trust  the court considered that the determination of the adequacy of the inspection pertaining to the tree’s condition was inextricably linked to the location of the tree. In that case the Trust was found to have fulfilled its duty in not carrying out remedial action for an identified defect when the location of the tree was taken into account.
The Courts have always been slow to find liability where damage or injury is caused by an “unobservable course of nature”, Noble v Harrison . Therefore, if a defect in the tree is not identifiable by reasonable inspection then it is unlikely liability will attach should injury or damage be caused by its subsequent collapse. Clearly this is an evidential issue. The problem that is often faced in defending claims resulting from catastrophic tree failure is that evidence of the condition of the tree has been destroyed or degraded. The defendant is therefore in a position of trying to prove a negative.
In Micklewright v Surrey County Council  the inspection regime was found to have been essentially non-existent but the court found that no liability would attach to the defendant as the defect would not have been detected in any event.
The above raises two practical challenges to be addressed by Local Authority defendants:
record keeping of inspections carried out; and
that in the event of catastrophic tree collapse photographic and other evidence be obtained in respect of the tree and the surrounding locus by a person with reasonable arboricultural knowledge as quickly as possible after the event.
Evidently if a defect could have been identified on a reasonable inspection, the tree was located in an area which warranted it to be inspected but no inspection had been carried out the court will, unsurprisingly, find in favour of the claimant (e.g. Quinn v Scott ).
Adequacy of inspection and inspection regime
The HSE Sector Information Minute “Management of the risk from falling trees and branches”, states:
…for trees in a frequently visited zone, a system for periodic, proactive checks is appropriate. This should involve a quick visual check for obvious signs that a tree is likely to be unstable and be carried out by a person with a working knowledge of trees and their defects, but who need not be an arboricultural specialist. Informing staff who work in parks or highways as to what to look for would normally suffice”
To an extent, local authorities probably do this by default by way of their highway, housing and parks inspectors and inspections carried out by them. However, the courts have found that certain features of a tree (such as it being multi-stemmed or historic pruning wounds) should have put the landowner on notice of a defect and prompted a more detailed inspection. In Poll v Bartholomew  the High Court found that the presence of multi-stemmed ash tree along a roadside should have prompted a more detailed inspection which, if so done, would have revealed decay and prompted remedial action. Similarly, in Chapman referred to above the Court found that a pruning wound in the crown should have prompted a more detailed climbing inspection whereby the decay present in the crown would have been identified.
The reasoning in both cases is far from compelling and the best that can be taken from either is that certain features of a tree may warrant closer inspection. This area is so fact specific that no general principles can be said to have been established. Each case will very much be decided on its own facts.
Defendable tree risk management requires an exercise in categorising areas of risk which necessarily requires a relatively good knowledge of the tree stock.
A reasonable tree safety strategy for a council or large landowner requires that the owner has oversight of their tree stock with respect to its distribution and the level of use in the vicinity of trees.
As management requires a sensible resource allocation, categorisation of areas of trees will facilitate how resources are prioritised and allocated.
A tree safety policy will also take account of the level and frequency of inspection and the appropriate level of competence of carrying out tree safety management including inspection.
However, without evidence of practices employed in tree risk management a significant evidential challenge is posed in establishing a defence against claims in relation to tree collapse. Record keeping of tree inspections, relevant decision making and evidence of zoning provide such evidence.
This information is intended as a general discussion surrounding the topics covered and is for guidance purposes only. It does not constitute legal advice and should not be regarded as a substitute for taking legal advice. DWF is not responsible for any activity undertaken based on this information.