To establish the tort of private nuisance involving encroachment of Japanese knotweed, the claimant must establish that breach of duty by the defendant caused the loss suffered. The question is would the diminution in value of which the claimant complains have occurred “but for” the breach of duty by the defendant? If the diminution in value would have occurred in any event, there is no causal link between the breach of duty and the diminution in value and no claim.
The Supreme Court has allowed the council’s appeal against liability and damages in Davies v Bridgend County Borough Council [2024] UKSC 15; [2024] PLSCS 86.
The case concerned property in Bridgend, Wales acquired by Marc Davies in 2004, which adjoined land owned by the council. Long before 2004, Japanese knotweed spread from the council’s land onto the property. By 2013 the council was, or ought to have been, aware of the dangers of Japanese knotweed which it knew or ought to have known was growing on its land, but it was not until 2018 that it implemented a reasonable and effective treatment programme.
Davies brought a claim in nuisance, seeking damages for diminution in value of the property, including for the cost of treatment, for disturbance and inconvenience, and £4,900 for the residual diminution in value of the property or “blight” remaining after treatment of the knotweed. The judge at first instance found that the council was in continuing breach of its duty during the period 2013-2018 but that damages for diminution in value were irrecoverable. His decision was upheld on a first appeal.
The Court of Appeal upheld the finding of continuous breach. 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. This is pure economic loss. However, once knotweed rhizomes are present on the claimant’s land, its 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. It allowed Davies’ appeal and awarded damages of £4,900.
The Supreme Court unanimously allowed the council’s appeal. 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. So, applying the “but for” test eliminated the council’s subsequent breach of duty as a causative factor. No damages were payable.
Louise Clark is a property law consultant and mediator
