Sateeshkumar: First Appeal on Causation in Nuisance Claims

Judgment has been handed down in Sateeshkumar v Wigan Council [2026] EWCC 39, in the first appeal on the question of whether a claimant must show causation to rely on Delaware Mansions to argue that the cost of treating Japanese knotweed is a cost of abating a nuisance.

The issue follows from the Supreme Court’s decision in Davies v Bridgend County Borough Council [2025] AC 434, where I made a concession for the claimant at trial, and did not resile in the subsequent appeals, that the cost of treatment would fail on the normal ‘but for’ test. The causation argument in Davies therefore related to residual diminution in value and whether that could still be maintained as a claim akin to an avoidable period of additional loss.

The judgment of Lord Stephens in Davies made clear that the Supreme Court was not commenting on whether that concession was rightly made (para 35):

“No issue arises on this appeal as to whether the concession was correct or whether the claim for the costs of treatment might be recoverable as a reasonable cost in abating the nuisance…”

In subsequent cases, claimants have argued that the cost of treating Japanese knotweed on their land can be recovered as the cost of abating a continuing nuisance, relying on Delaware Mansions, regardless of whether or not it encroached before any breach of duty by the defendant.

In Sateeshkumar, the trial judge found that the claimants could rely on that principle, and dismissed the claim for diminution in value but allowed the cost of treatment as the cost of abating a continuing nuisance. That was so despite the knotweed encroaching before 2018, when the defendant first came under a duty.

On appeal, HHJ Pearce has now held the opposite. The unsuccessful claimant will almost certainly ask for permission for a second appeal to the Court of Appeal, which is likely be granted as a point with a real prospect of success and public importance. Until that comes out in the wash, this appeal provides useful guidance for other cases.

During submissions in Davies, Lord Reed commented on Delaware having been a case that did not appear to have been thought of as hugely important at the time but which has caused a number of issues for many years. The question of causation is one such difficulty which was not considered in Delaware.

In this appeal, the judge ultimately found that a claimant must always establish causation and that Delaware is not an exception to this. The decision is summarised at the end of the judgment (para 49):

“For these reasons, I am persuaded that the true extent of the Defendant’s liability is for losses (including the reasonable cost of eradicating JKW) incurred as a result of the spread of the JKW onto the Claimant’s land that would have been avoided had the Defendant not been in breach of duty, in other words, had the Defendant taken reasonable steps to eradicate JKW on its land once it was aware (or ought to have been aware) of the presence of the JKW on its land. On the facts as found by the Judge below, no such losses arose after the Defendant became in breach of duty by reason of its failure to act as a reasonable neighbour by eradicating JKW of which it knew or ought to have known, the JKW having by then already spread to the Claimant’s land”

As a result, if knotweed encroached before the defendant owed a duty, as in Davies, a claimant who had knotweed in their garden cannot recover the cost of treating it against the defendant by packaging the claim as one of abating a continuing nuisance, rather than as a claim for damages.