Louise Clark analyses a recent Supreme Court ruling on private nuisance involving Japanese knotweed
Key points
- Liability for nuisance requires the breach of duty to have caused the loss suffered
- Is the “but for” test satisfied?
- If the loss would have occurred anyway there is no causal link and no claim
The Supreme Court has gone back to basics in considering the tort of private nuisance by encroachment of Japanese knotweed in Davies v Bridgend County Borough Council [2024] UKSC 15; [2024] PLSCS 86.
Background
The case concerned property in Bridgend, Wales, acquired by Marc Davies in 2004, which adjoined land owned by Bridgend County Council. Well before 2004, Japanese knotweed spread from the council’s land onto the property. At that time there was no actionable tort of private nuisance against the council.
However, such a claim arose in 2013 when the council was, or ought to have been, aware of the risk of damage and loss of amenity to the property as a result of publicly available information on Japanese knotweed and it failed to implement a reasonable and effective treatment programme in relation to the Japanese knotweed, which it knew or ought to have known was growing on its land. It was not until 2018 that such a programme was implemented.
Davies brought a claim in nuisance, seeking various sums including damages of £4,900 (7% of the unaffected market value of the property) for residual diminution in value of the property or blight which he claimed existed despite the treatment, because the evidence was that infestations of Japanese knotweed could be managed but not wholly eradicated.
The defendant contended that the claim for residual diminution in value was fatally flawed since it was caused by the non-actionable presence of Japanese knotweed on the land well before 2004 and before the defendant’s breach of duty in 2013.
Williams v Network Rail
The district judge, circuit judge and the Court of Appeal all considered Williams and another v Network Rail Infrastructure Ltd [2018] EWCA Civ 1514; [2018] PLSCS 120, where the claimants succeeded in claims in private nuisance for interference with their quiet enjoyment/loss of amenity against Network Rail for the effects of Japanese knotweed on their properties, which Network Rail had allowed to grow on its adjacent land.
The presence of Japanese knotweed affected the claimants’ ability to sell their properties at a proper market value because, since 2012, mortgage lenders limited or refused to provide mortgages where Japanese knotweed was within seven metres of the property’s boundary.
The Court of Appeal, while rejecting Network Rail’s appeal, considered this approach to be wrong in principle. The purpose of the tort of nuisance is to protect the owner of land in their use and enjoyment of the land, not its value.
The “but for” test in relation to causation
To establish liability for private nuisance involving the encroachment of Japanese knotweed rhizomes from the defendant’s land onto the claimant’s land, the claimant must establish that the defendant’s breach of duty did in fact cause the loss suffered.
The “but for” test eliminates irrelevant causative factors. The question is whether the diminution in value of which the claimant complains would not have occurred “but for” the breach of duty by the defendant. If the diminution in value would have occurred in any event, then the defendant’s breach of duty is eliminated as a cause and there is no causal link between the breach of duty and the diminution in value.
While there are exceptions to this test, they were not considered relevant in this case.
Decisions below
The judge at first instance found that the council was in continuing breach of its duty during the period 2013-2018 because there were further encroachments of Japanese knotweed rhizomes from its land onto the claimant’s land during this period and that the continuing nuisance caused the diminution in value.
However, the damages were irrecoverable because they were pure economic loss. His decision was upheld on a first appeal. Both judges relied on Williams to support their decisions.
The Court of Appeal upheld the finding of continuous breach but considered that both judges had misunderstood the decision in Williams.
There is no actionable nuisance caused by Japanese knotweed on a defendant’s land simply because it diminishes the market value of the claimant’s land for reasons of policy which characterises the claim as pure economic loss.
However, once knotweed rhizomes are present on the claimant’s land their quiet enjoyment or the amenity value of the land is diminished. This amounts to damage as a result of the physical interference and, if consequential residual diminution in value can be proved, damages are recoverable.
A claimant is entitled to recover the reasonable costs incurred in abating a continuing nuisance (Delaware Mansions Ltd v Westminster City Council [2001] UKHL 55). The Court of Appeal allowed Davies’ appeal and awarded damages of £4,900.
Supreme Court decision
The question for the Supreme Court was a narrow one. Was the residual diminution in value of the claimant’s land caused by the defendant’s breach of duty in private nuisance? Unanimously, the Supreme Court allowed the council’s appeal.
Delaware was not authority for the proposition that diminution in market value is recoverable, regardless as to whether the diminution occurred prior to the defendant’s breach of duty.
There was no finding by the judge at first instance that the defendant’s breach of duty for the period 2013-2018 had increased or materially contributed to the diminution in value of Davies’ land.
The diminution in value had occurred long before 2013. The application of the “but for” test eliminated the council’s subsequent breach of duty as a causative factor. The diminution in value would have occurred in any event. No damages were payable.
Louise Clark is a property law consultant and mediator
