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On 3 July 2018, the Court of Appeal handed down its decision in the case of Network Rail Infrastructure Limited –v- Stephen Williams and Robin Waistell on the very important issue of private nuisance caused by Japanese Knotweed, the pernicious perennial plant.

As many of you will know, this destructive plant can affect the value of property and can be expensive and difficult to treat, with problems being caused to neighbouring properties if it is not treated. This case is therefore an important decision for those who have suffered at the hands of Japanese Knotweed growing on neighbouring land.

Decision at first instance

In 2015 Mr Williams and Mr Waistell (“the claimants”) brought claims for private nuisance against Network Rail in the Cardiff County Court. They claimed that Network Rail had Japanese Knotweed growing on adjoining land (which had been present for at least 50 years) and which had caused damage to the claimants’ properties.

The County Court rejected the claim in nuisance based on encroachment of the Knotweed under the claimants’ bungalows (“the encroachment claim”). It was held that whilst there was evidence of encroachment of the Japanese Knotweed on Mr Waistell’s land, and on the balance of probabilities, encroachment on Mr Williams’ land, the claimants needed to establish that they had suffered physical damage to their properties. Neither of their experts identified damage to the properties, and diminution in value did not constitute damage for the purpose of that claim.

The claimants were however successful on their claims based on quiet enjoyment and loss of amenity. It was held that Network Rail’s failure to treat the Japanese Knotweed, even before the claimants had complained about it, was not commensurate with Network Rail’s duty as a landowner as they had constructive knowledge of the presence of the Japanese Knotweed on their land. It was also found that they failed to treat it so as to reasonably prevent interference with the claimants’ quiet enjoyment. Network Rail’s actions after the claimants had complained were also unreasonable.

It was recorded that “the unlawful interference with the claimants’ quiet enjoyment of their properties, by virtue of the presence of the knotweed and the impact upon use and enjoyment of the properties because they were reduced in market value, was caused by the presence of Japanese Knotweed on NR’s land which amounted to continuing nuisance.”

Whilst the County Court found that it was not appropriate to grant an injunction to compel the treatment of the Japanese Knotweed as it would be vague and uncertain, damages were awarded to Mr William and Mr Waistell.

Network Rail subsequently appealed the decision, and the Court of Appeal handed down its decision on 3 July 2018.

The principles of nuisance

During the course of his judgment dated 3 July 2018, Sir Terence Etherton MR helpfully summarised the five present principles of the cause of action of nuisance as follows:

  1. It is a violation of real property rights, in other words, it involves either an interference with the legal rights of an owner of land, or an interference with the amenity of the land.
  2. Whilst nuisance is sometimes broken down into different categories, those categories are merely examples of a violation of property rights.
  3. The proposition that damage is always an essential requirement of the cause of action must be treated with considerable caution and is not entirely correct. The concept of damage in the context of nuisance is a highly elastic one, and so far as damage from an artificial object, the better view may actually be that damage is formally required but damage is always presumed. In the case of nuisance through interference with the amenity of land, physical damage is not necessary to complete the cause of action. What is relevant is the objective effect on the amenity value of the land itself, and it is that effect which satisfies any requirement there may be to show damage.
  4. Nuisance may be caused by inaction or omission as well as by some positive activity.
  5. The broad unifying principle in this area of law is reasonableness between neighbours.

Court of Appeal’s decision

Whilst the claimants were successful in opposing the appeal, with the Court of Appeal upholding the original decision of the County Court, the Court of Appeal did so for different reasons. The Court of Appeal held that:

  • They did not agree with the analysis and decision of the County Court in rejecting the encroachment claim.
  • Nuisance was committed when the encroachment of the Japanese Knotweed diminished the utility and amenity of the claimants’ properties.
  • In appropriate circumstances, a claimant should be able to obtain a final mandatory injunction where the amenity value of the land is diminished by the presence of roots, even though there has not yet been any physical damage.
  • There is no reason why the legal position concerning nuisance caused by the encroachment of roots etc. should undermine the right of the Claimants to claim damages by reason of the encroachment.


This case is a warning to those owning property to take care to ensure that they properly treat any Japanese Knotweed on their land, not only so as to protect their property, but so as to avoid the possibility of a claim for nuisance even when there is no physical damage to neighbouring property. It is also a continued reminder to practitioners of the importance of enquiries relating to Japanese Knotweed. Finally, as they will already be aware, surveyors must continue to be alive to this issue when carrying out their inspections.

All in all, it is a continued warning to all, and a helpful decision for property owners affected by neighbours’ pernicious Japanese Knotweed.

The contents of this article are intended for general information purposes only and shall not be deemed to be, or constitute legal advice. We cannot accept responsibility for any loss as a result of acts or omissions taken in respect of this article.