Diminution of value from Japanese knotweed on own land is not actionable nuisance but presence of roots without actionable damage is actionable nuisance (Court of Appeal)
On 3 July 2018, the Court of Appeal (Sir Terence Etherton, Sharp and Leggatt LJJ) upheld the decision of the County Court in relation to a claim in nuisance for Japanese knotweed, but for different reasons.
The court decided that the defendant, Network Rail, had caused an actionable nuisance by failing to take reasonable steps to prevent an invasive plant, Japanese knotweed, from blighting domestic properties next to its railway embankment.
The court said that the recorder had erred in finding that the presence of Japanese knotweed was an actionable nuisance because it diminished the market value of the neighbouring properties (this would extend the tort to a claim for pure economic loss). However, the court said that the risk of future physical damage from the knotweed, the increased difficulties for landowners in developing due to the presence of the rhizomes, Network Rail’s knowledge of the presence of the knotweed and its failure reasonably to prevent the interference with the respondents’ enjoyment of their properties were sufficient to give rise to a cause of action in nuisance.
The Court of Appeal also set out a useful summary of the general principles of nuisance under current case law. (Network Rail Infrastructure Ltd v Williams and another  EWCA Civ 1514.)