Court of Appeal rules on a private nuisance claim arising from encroachment of Japanese knotweed – of possible interest to liability insurers

The claimants brought claims in private nuisance after Japanese knotweed spread from their neighbour's land onto their land. The Japanese knotweed had not caused any physical damage to the claimants' properties, or any change in the soil structure on their land. However, the value of properties affected by Japanese knotweed can be reduced.

The claimants presented their private nuisance claims in two ways: 1) an "encroachment claim" (ie the neighbour was liable because the Japanese knotweed had spread to their land (even though there was no damage); and 2) a "quiet enjoyment/loss of amenity claim". The recorder at first instance held that the encroachment claim failed, because of the lack of physical damage to the claimant's property, but the quiet enjoyment claim succeeded. On appeal, the Court of Appeal has now held as follows:

  1. Although actions for nuisance are sometimes broken down into different categories, these are only examples of a violation of property rights: "The difficulty with any rigid categorisation is that it may not easily accommodate possible examples of nuisance in new social conditions or may undermine a proper analysis of factual situations which have aspects of more than one category but do not fall squarely within any one category, having regard to existing case law".
  2. The proposition that damage is always an essential requirement of the cause of action for nuisance "must be treated with considerable caution". For nuisance from encroachment by an artificial object "the better view may actually be that damage is formally required but damage is always presumed".
  3. Furthermore, "The purpose of the tort of nuisance is not to protect the value of property as an investment or a financial asset. Its purpose is to protect the owner of land (or a person entitled to exclusive possession) in their use and enjoyment of the land as such as a facet of the right of ownership or right to exclusive possession". Accordingly, the recorder had erred in finding that the pure economic loss which the claimants had suffered because of the Japanese knotweed (as a result of the diminution in the value of their property) gave rise to actionable private nuisance.
  4. However, nuisance was committed when the Japanese knotweed encroached onto the claimants' properties as it had diminished the utility and amenity of the claimants' properties.