Private Nuisance by Japanese Knotweed

Network Rail Infrastructure Ltd v Williams and Waistell [2018] EWCA 1514, 3 July 2018

Japanese knotweed is a fast-growing plant that can disrupt drains, paving and walls. It spreads by means of rhizomes, ie underground stems, and is difficult to get rid of, partly because it can regrow from any small section of rhizome that is left in the soil. Soil contaminated with Japanese knotweed is designated ‘controlled waste’ under the Environmental Protection Act 1990 and can only be removed and disposed of by licensed organisations. The presence of Japanese knotweed on or near land can reduce its market value, and mortgage lenders frequently insist on costly remedial measures before they will lend money to someone intending to purchase land with the weed growing either on it or within 7 metres of it.

The case involved claims in private nuisance by the owners of two adjoining semi-detached bungalows in Maesteg, South Wales. The defendant, Network Rail Infrastructure Ltd, had allowed Japanese knotweed to grow on its land – a railway embankment – abutting the claimants’ properties. The trial judge – Mr Recorder Grubb – found that the defendant had failed to take adequate or reasonable steps to deal with the issue even after it had notice of the risk of the knotweed interfering with the claimants’ use and enjoyment of their land.

The main issue for the Court of Appeal was whether the claimants had suffered anything that could constitute a private nuisance. The Recorder had found that the knotweed had intruded (‘encroached’) under the claimants’ properties, but that it had not caused any physical damage. He found that the defendant was liable to the claimants, however, on the basis that the owner of a property blighted by the presence of knotweed on neighbouring land could establish an interference with the amenity value of the land as a result of his or her concerns about the effect of the knotweed on the value of the property.

The Court of Appeal held that the Recorder’s basis for finding liability was ‘wrong in principle’. The Court’s primary objection was that a simple devaluation of land is pure economic loss – that is, loss not consequential on physical damage or an interference with rights in land – and that an owner’s concerns about such devaluation could not change the nature of the harm so as to bring it within the sphere of private nuisance. With respect, this is clearly correct: if an owner’s ongoing concerns about property values could turn any substantial devaluation into a private nuisance then the scope of the tort would be greatly expanded, and there would be a significant increase in the number of activities of neighbouring landowners that had to be assessed for ‘reasonableness’. There are many activities that can affect property values but which do not interfere with a claimant’s right to use and enjoy his or her land. For example, advertising a residential property as available for rental by students – as opposed to by families – would lead to a reduction in value of neighbouring properties in many parts of Oxford – as a result of student tenants having a (perhaps unfair) poor reputation as neighbours: but surely a defendant should not be obliged to demonstrate the reasonableness of subjecting his or her neighbours to such worries about the value of their properties? To put the same point another way, a property owner does not have a right that his neighbour uses his or her land only in ways that potential purchasers would be happy about living next door to.

The Court of Appeal dismissed the defendant’s appeal, however, by concluding that the Recorder should have straightforwardly found in the claimants’ favour by relying on the contamination of their soil by knotweed rhizomes. In the words of Sir Terence Etherton MR, who wrote the main judgment, at [55]: ‘the mere presence of [Japanese knotweed] rhizomes, imposes an immediate burden on the owner of the land in terms of an increased difficulty in the ability to develop, and in the cost of developing, the land, should the owner wish to do so. [And] … any improvement or alteration of the property requiring the removal of contaminated soil would require disposal of the soil either on site or, more likely, off site by special, and probably expensive, procedures.” He thought that the presence of Japanese knotweed and its rhizomes “are a classic example of an interference with the amenity value of the land.’

Personally, I would have been inclined to treat the contamination of soil by the presence of rhizomes as a form of physical damage – similar to the claim for the deposit of excess dust in carpets that was discussed by the Court of Appeal in Hunter v Canary Wharf Ltd [1997] AC 655, at 676 (Pill LJ). But, however the effect is conceptualized, it is clear that the Network Rail case limits the scope of private nuisance by prioritizing physical interferences (intrusion, emanation, contamination, obstruction, withdrawal of support, etc) over other annoyances and inconveniences (unfriendly neighbours, an untidy neighbouring garden, closure of the local pub or post office, etc).

The case leaves three significant follow-on questions only partially answered.

  1. Can a claimant make a claim against a defendant who has Japanese knotweed on its land even before the rhizomes intrude into the claimant’s soil? The answer to this appears to be that the claimant will not be able to claim simply because he or she is worried about the situation, still less because the market value of his or her property has fallen, but he or she may be able to seek a quia timet injunction where the prospect of physical intrusion and contamination is sufficiently likely.
  2. What is the current status of the ‘affront’ cases, such as Thompson-Schwab v Costaki [1956] 1 WLR 335 and Laws v Florinplace Ltd [1981] 1 All ER 659, where the claimants do seem to have based their claims on their concerns about what was happening on neighbouring land (respectively, prostitution and the opening of a ‘Sex Centre and Cinema Club’)? Sir Terence Etherton MR discussed these cases in his judgment in the Network Rail case, but appeared to distinguish them on the basis that in them the evident nature of the neighbouring activities was causing the interference with the claimants’ enjoyment of land, as opposed to causing a devaluation in property which then worried the claimants.
  3. Where an occupier has Japanese knotweed on its land that could foreseeably spread and cause problems for neighbours then what steps must it take in order to behave reasonably vis-à-vis those neighbours? This question was not one that the Court of Appeal had to confront. But clearly the decision that Network Rail Infrastructure Ltd can be liable for allowing Japanese knotweed to continue growing on a railway embankment – where it had apparently been growing for at least 50 years – is likely to make the question important. The case of Holbeck Hall Hotel Ltd v Scarborough BC [2000] QB 836 suggests that where a private nuisance may arise as a result of a natural hazard it may be appropriate to consider how far both defendant and claimants are likely to benefit from removal of the hazard, and the resources available to both defendant and claimants, when deciding what can reasonably be expected. In cases involving tress roots, however, it seems that defendants generally bear the cost of protective measures. As a result, the issue may only be settled by further litigation.


Roderick Bagshaw (uploaded- 3 July 2018)

About tortox

Teaches and researches tort law in Oxford, UK.
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