Japanese Knotweed: A private nuisance to landowners

Williams and another v Network Rail Infrastructure Ltd  [2018] EWCA Civ 1514; [2018] PLSCS 120

Over the past few years there has been increasing awareness about the significant threat posed by Japanese Knotweed, not only to plant biodiversity but to hard structures, including buildings and flood defences. Although not native to the UK, this invasive weed  has spread like wildfire following its introduction to the UK by the Victorians around 1886 as an ornamental plant. 

Last month saw the conclusion of a four year 'David and Goliath' style battle fought between two next door neighbours, whose properties were blighted by Knotweed growing on railway embankments, and Network Rail.

The two homeowners applied for an injunction to require Network Rail to treat the Japanese Knotweed on their land. They also claimed damages for a private nuisance based upon an encroachment by the knotweed.

At first instance, the court found  that no actual physical damage had been caused by the encroachment of the knotweed. In addition, although there was a diminution in the value of the claimants' bungalows, this did not constitute damage. The Court held that, in the absence of physical damage, this was not a claim in private nuisance.

Despite not finding that there was a private nuisance in respect of the encroachment of the knotweed, the court  awarded  the claimants damages equivalent to the costs of treating the invasive knotweed and for the diminution in the residual value of the bungalows resulting from the presence of knotweed and its interference with the quiet enjoyment or amenity value of their properties.

Network Rail appealed against this judgement.

The grounds of appeal included an assertion that the court at first instance was wrong to find that the pure economic loss suffered by the claimants resulting  from the diminution in value of their bungalows after the discovery of knotweed constituted an actual private nuisance because it interfered with the quiet enjoyment of the bungalows. The Court of Appeal agreed. It held that private nuisance was not concerned with the value of land. It does not extend to pure economic loss. The court of appeal confirmed that the purpose of private nuisance is to protect the use and enjoyment of Property.

Although Network Rail succeeded this part of their appeal, the court of appeal further found that the court at first instance was wrong to conclude that there was not private nuisance as a result of the encroachment of the knotweed from the railway embankment. Knotweed could be described as a natural hazard and as a result can affect a property owner's full use and enjoyment of their land.

The court of appeal noted the court of first instance's findings in regard to Network Rail's knowledge as to the presence of knotweed and its failure to reasonably prevent interference with the claimants' use and enjoyment of their land. As such, it did not interfere with the damaged awarded to the claimants at first instance.

So what can we learn from this landmark case?

  • The Court of Appeal clarifies that, where Japanese knotweed is encroaching on their land, landowners do not have to wait to show physical damage to their properties to bring an actionable claim for private nuisance.

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