Knotweed as a nuisance – landmark legal ruling for landowners

The recent Court of Appeal judgment ruled that landowners may be entitled to sue under the law of private nuisance if Japanese Knotweed on…

The recent Court of Appeal judgment in Network Rail Infrastructure Limited v Williams and Waistell [2018] EWCA Civ 1514 has ruled that landowners may be entitled to sue under the law of private nuisance if Japanese Knotweed on neighbouring land interferes with a landowner’s enjoyment of their land.

Williams and Waistell (the “claimants”) owned properties next to land owned by Network Rail, which was known to contain knotweed.

In 2015 the claimants brought a claim in private nuisance against Network Rail, seeking an injunction to require Network Rail to treat and eliminate the knotweed, and damages.

Under the “encroachment claim” the claimants argued that Network Rail was liable for encroachment of the knotweed upon their land. This part of the claim was rejected as it was held that no actual physical damage had been caused by the encroachment, so the encroachment did not give rise to a claim in private nuisance.

The court did however allow the “quiet enjoyment/loss of amenity claim”. It said there was an unlawful interference with the claimants’ quiet enjoyment of their properties, by virtue of the presence of the knotweed and the impact upon the use and enjoyment of the properties and the reduction in market value. The court held this gave rise to an actionable claim in private nuisance.

Due to the knowledge of the presence of knotweed and the risk that it posed, Network Rail had a duty to do all that was reasonable in the circumstances to prevent or minimise the effect on nearby properties. Network Rail had breached this duty, so damages totalling nearly £31,000 were granted to cover a treatment package for the knotweed and for loss of amenity and quiet enjoyment of the claimants.

Network Rail appealed the judgment on the grounds that, where a residual homeowner suffers a diminution in the value of their property by virtue of the presence of knotweed, the pure economic loss which is suffered does not constitute an actionable private nuisance. The Court of Appeal agreed and said that the decision in the 'quiet enjoyment/loss of amenity claim' "extend[ed] the tort of nuisance to a claim for pure economic loss" which would "not be an incremental development to the common law by way of analogy, but a radical reformulation of the purpose and scope of the tort". The Judge was of the view that the purpose of the tort of nuisance was not to protect the value of a property as an investment or financial asset, but to protect the use and enjoyment of land.

However, the appeal judgment upheld the decision that there was a loss of amenity, on the basis that the knotweed carries the risk of future physical damage to buildings, structures and installations on the land. Its presence, and the presence of its 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, thus affecting the owner’s ability to fully use and enjoy the land. The court concluded that this was a “classic example of an interference with the amenity value of the land”.

The judgment in this case is significant for a number of reasons:

  1. It places a duty of care on landowners to ensure that knotweed will not spread from their land to neighbouring properties.
  2. Landowners must take reasonable steps to prevent or minimise encroachment of knotweed onto adjoining land.
  3. Even if knotweed encroachment onto neighbouring property does not result in actual physical damage to the property, the affected landowner could claim for loss of amenity value of the land due to the presence of knotweed.

In light of this judgment it will now be essential that landowners with knotweed on their land consider how they are going to ensure that it does not spread and take action to prevent it from doing so. Although long term treatment of knotweed could place a financial burden on a landowner, the consequences of not treating it could be even more costly.

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