A knotty issue from County to Supreme Court

The case of Davies v Bridgend County Borough Council [2024] UKSC 15 addressed diminution in value of land from damage caused by Japanese knotweed and the application of the "but-for" test.

 

Background to the claim

Japanese knotweed is an invasive species of plant which can cause significant damage to buildings and land and is extremely difficult to remove. As a result, where Japanese knotweed is present on a property it can have a negative impact on property values. In this case, the landowner, Mr Davies, lived next to land owned by Bridgend County Borough Council. Prior to his acquisition of the land in 2004, knotweed had spread from the Council's land onto Mr Davies' land. The Council did not implement an effective treatment of the knotweed until 2018.

Mr Davies brought a claim in the County Court against the Council in 2020, seeking damages for (amongst other things) the residual diminution in value of his land following treatment in the sum of GBP4,900. This diminution in value was said to have occurred despite the effective treatment of the knotweed, due to the "stigma" or "blight" associated with the plant in the mind of future purchasers.

It was established that the Council knew, or ought to have known, in 2013 that the knotweed presented a foreseeable risk of harm to Mr Davies' land based on the published material available at that time. The judge therefore found that the Council had caused a continuing nuisance between 2013 and 2018. However, the original encroachment of knotweed on to Mr Davies' land, which occurred well before 2004, was non-actionable.

In the County Court, the judge refused Mr Davies' diminution claim on the basis that it constituted pure economic loss.

 

Appellate history

The matter made its way through the courts on a series of appeals. Mr Davies' first appeal failed. However, his second appeal to the Court of Appeal was successful. The Court of Appeal concluded that as the residual diminution in value was harm, which occurred at the end of the period of a continuing nuisance, it was harm caused by the continuing breach. Accordingly, the Court of Appeal allowed Mr Davies’ appeal.

 

Supreme Court ruling

In 2024, the issue of whether Mr Davies was entitled to GBP4,900 in damages reached the Supreme Court on a third appeal.

It was the Council's position that even if there was a continuing nuisance between 2013 and 2018, any residual diminution in value had already been incurred by the original, and non-actionable, encroachment of knotweed which had occurred before Mr Davies purchased the land. The Supreme Court agreed, and unanimously ruled that the diminution in value was not caused by the Council and no damages were to be awarded.

In reaching the decision, the Supreme Court applied the "but for" test: would the diminution in value have occurred, but for the wrongdoing of the Council between 2013 and 2018? On the facts, no evidence had shown that the Council's breach of duty between 2013 and 2018 had materially contributed to the diminution in value of Mr Davies' land. The diminution in value was therefore found to have occurred before any breach and a causal link could not be established between the Council's actions and the damages claimed.

 

Commentary

It may seem surprising that a case of this value reached the Supreme Court, following two rounds of appeals. The central issue concerning factual causation no doubt holds significant legal importance and its application to the tort of private nuisance has rarely been given this level of attention. It will also give some comfort to any parties facing claims in damages for historic encroachment of Japanese knotweed. Nevertheless, the principle of proportionality should not be overlooked, regardless of the subject matter. At the Court of Appeal stage, Lord Justice Birss made the passing remark:

"Before going further, I note that what is in issue in terms of damages here is GBP4,900. If that was all that was at stake, the proportionality of these proceedings having got this far would be questionable, but the principle is an important one, and no doubt (sadly) the costs are substantial."

The facts and judicial timeline of this case serve as a salient reminder of the importance of pragmatism at all stages of litigation, particularly where costs in the case are estimated to run wildly over and above the value of the claim itself.