REUTERS | Mike Blake

Tree roots: causation in natural nuisance cases

What is the correct approach to causation in cases concerning natural nuisances where a landowner does nothing at all to abate such a nuisance on his land?

That was the question for the Court of Appeal in Robbins v London Borough of Bexley, a case that concerned property damage caused by tree roots.

Robbins v London Borough of Bexley

The claimant (Mrs Robbins) purchased a house in Kent in 1969. In 1996, a homeowner in the same street made a claim against the defendant (the Council) for damage caused by tree roots emanating from the Council’s land. Despite the damage and the neighbour’s claim, the Council did not implement a scheme of crown reduction of the trees between1998 and 2006 to reduce the risk of damage.

In summer 2003, the tree roots from the Council’s land caused damage to Mrs Robbins’ house. In 2004 and 2005, the Council ordered work to be carried out on the offending trees. That work was to comprise a 25% crown reduction in the trees. However, that work was not carried out. In summer 2006, the tree roots caused further damage to Mrs Robbins’ house. Subsequently, in September 2006, the Council’s contractors carried out very significant crown reductions to the trees, in amounts exceeding the Council’s instructions.

At first instance

At first instance, Edwards-Stuart J held the Council liable in negligence for the damage to Mrs Robbins’ property caused by the tree roots emanating from it’s land. In doing so, he found that:

  • From early 1998, the Council knew that the trees were capable of causing damage to any rear extension along Mrs Robbins’ road within 35 metres of the trees and that Mrs Robbins’ home was at real risk of subsidence.
  • From 1998 onwards, the Council could reasonably have been expected to embark on a programme of cyclical crown reductions and should have done so. The prevailing expert advice was a cycle of three to four years, with not more than 30% of the tree canopy being removed in each cycle.
  • In May 2004, the Building Research Establishment’s (BRE) Horticulture LINK project 212, Controlling water use of trees to alleviate subsidence risk (Hortlink) was published. Hortlink concluded that it was necessary to reduce crown volume by 70-90% to reduce soil desiccation.
  • Crown reduction of 25% would have had no effect on soil desiccation.
  • The Council did nothing between 1998 and 2006.
  • If the Council had put in place a cyclical pruning programme in 1998, the trees would have received the type of treatment they received in 2006, namely a significant reduction by the Council’s contractors in excess of that instructed by the council.
  • Had the Council implemented any form of cyclical pruning programme in 1998, this would have reduced the crowns of the trees by an amount necessary to avoid damage to Mrs Robbins’ property.

The Council’s appeal

The Council appealed. Its principal ground of appeal was:

  • The expert evidence showed that the Council should have reduced tree crowns by 25% every three to four years from 1998, but that 25% would have had no effect in any event. Thus, any breach of duty by the Council did not in fact cause the damage to Mrs Robbins’ property.
  • Therefore, the true cause of the damage was the Council’s failure to take steps that were never its duty to take before 2006, namely very significant crown reductions in excess of those in fact instructed subsequently.

The council argued:

  • That the judge was wrong to ask what would the Council have done if it had taken steps to prevent damage.
  • Instead, the judge should have asked what should the Council have done.
  • If the judge had asked what should the Council have done, that factual enquiry would have been answered by reference to the accepted duty at the time, namely a 30% crown reduction only (which would not have been sufficient to prevent the damage to Mrs Robbins’ property).
  • In any event, the judge was wrong to make a factual finding that between 1998 and 2006 the crown reductions on the offending trees that the Council’s contractors should have carried out would have been as extensive as those in 2006.

The law of causation

The following points of principle can be extracted from the case law:

  • In cases where the breach of duty consists of an omission, a failure to act at all, to do something that ought to be done (for example, in Robbins, implementing any form of crown reduction from 1998 onwards) with a continuing duty to act, there must be a further factual enquiry. What would the party in breach have done if it had complied with its duty, namely, what would the Council (and its contractors) have done if the Council had taken steps to prevent the tree roots damaging Mrs Robbins’ property?
  • In cases where the breach of duty consists of an omission to do an act that ought to be done, but where there is no continuing duty to do anything further or where the duty gives rise to no further action on the defendant’s part, there is no need for any further factual enquiry.

In Robbins, the Court of Appeal applied Bolitho v City and Hackney Health Authority to the facts of the case. Robbins was an example of a situation where there was a continuing duty to act and the need for a further factual enquiry. The Court of Appeal rejected the Council’s attempted application of Beary v Pall Mall Investments, which was concerned with a situation where the duty in question gave rise to no further required action.

In Bolitho, a doctor was summoned but failed to attend a child suffering breathing difficulties. The judge (upheld by the Court of Appeal and House of Lords) held that the doctor was in breach of duty in failing to attend, and that intubation would have avoided the injury; but that, as a matter of fact, the doctor (non-negligently) would not have intubated had she attended. Accordingly, the Health Authority was held not to have caused the child’s brain damage.

It is worth noting that in Bolitho, the claim would have succeeded if the judge had found either that:

  • The doctor who negligently failed to attend would, as a matter of fact, have intubated if she had attended.
  • It would have been negligent not to intubate.

On the facts, the doctor would have had a range of non-negligent options available to her (including intubation), had she attended. The evidence was that she would not have intubated. Therefore, neither the negligent failure to attend nor the hypothetical actions of the doctor, had she attended, caused the damage.

In Beary, an independent financial advisor (IFA) negligently failed to advise his client of the possibility of taking out an annuity. The evidence was that the client would not have taken out the annuity, unless positively advised that he should. On the facts, the IFA owed no duty to his client to advise him further as to whether he should take out the annuity. The IFA’s negligence in failing to advice of the possibility of taking out an annuity caused no loss, as the client would not have done so, even if he had received that advice.

The Court of Appeal’s application of the law of causation

The Court of Appeal unanimously dismissed the Council’s appeal and upheld the judge’s finding in favour of Mrs Robbins’ claim:

  • The Council’s failure to put in place any programme of cyclical pruning caused the damage in 2003 and 2006.
  • The Council’s breach of duty was in not doing anything at all. That compares to the doctor not attending in Bolitho, which the Court applied.
  • Therefore, the facts demanded a further factual enquiry. What would have happened if the Council had done something rather than nothing?
  • The factual answer to that (as found by the judge at first instance) was that the Council’s contractors wouldhave executed crown reductions significantly in excess of the amount instructed by the Council, such that the damage to Mrs Robbins’ property would not have occurred.

Points of practice that arise

A number of points arise for practitioners from the Court of Appeal’s judgment:

  • In tree root and other natural nuisance cases:
    • if the defendant has done nothing at all, always consider not only what the defendant should have done, but moreover the further factual enquiry of what it would have done; and
    • if the defendant has taken at least some action to reduce the risk of damage, consider by reference to expert evidence whether its actions were reasonable.
  • Consider carefully all of the factual evidence as to what the defendant would have done, both before and after the alleged period of breach.
  • Unsuccessful parties in natural nuisance cases face great difficulty in successfully appealing questions of fact, especially from TCC decisions. Although not cited by the Court of Appeal in Robbins, the Court of Appeal’s comments in Skanska v Egger [2002] EWCA Civ 1914 are directly applicable:

“…decisions of the Technology and Construction Court have special characteristics which affect the readiness of the Court of Appeal to reconsider them on appeal.”

Difficult legal and factual issues of causation can often arise in cases involving natural nuisances. It is important at the outset of a dispute to have a clear understanding of the merits of such a claim, bearing in mind that each case is different and each will turn on its own particular facts.

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