This month, the Truro County Court (in the unreported case of Smith v Line) handed down a judgment which could impact owners of land containing Japanese Knotweed.

This is an important decision which builds upon a recent spate of cases concerning liability in nuisance for Japanese Knotweed. In particular, the case (as with the recent cases before it) holds landowners accountable for the Knotweed on their land, even before it causes any physical damage to neighbouring property.

Japanese Knotweed is an invasive plant, which is classified as controlled waste under the Environmental Protection Act 1990. It can cause substantial structural damage to tarmac, walls and buildings, and can considerably affect the value of property.

The facts of the case before the Truro County Court were as follows: Mr and Mrs Smith brought the court case against Mrs Line, who had sold them part of her land in 2002. Japanese Knotweed was present on Mrs Line’s retained land, and over the years, spread to the property purchased by Mr and Mrs Smith. The Smiths claimed that the mere presence of the weed on their land devalued their £500,000 property by 10%. Accordingly, the Smiths argued that Mrs Line was liable to them in the law of nuisance.

Nuisance is the legal term for when a landowner does, or omits to do, something on or with their land, which interferes with the use or enjoyment of neighbouring property, or which causes physical damage to neighbouring property. In this case, Mrs Line’s failure to eradicate the Knotweed on her land and stop it from spreading, devalued the Smiths’ property, and thus their ability to sell it. This, the court ruled, constituted an interference with the Smiths’ use and enjoyment of their land, rendering Mrs Line liable in nuisance. The court accordingly ordered Mrs Line to compensate the Smiths for the 10% reduction in the value of their property.

In light of cases such as this, precautions must be taken to prevent Knotweed from growing on property unchecked. If you find Knotweed on your land, you should arrange for this to be surveyed by a specialist contractor as soon as possible, and seek independent legal advice.

Similarly, you should see a solicitor if you are concerned about Knotweed growing on a neighbouring property. It may be that you can take legal action before the weed spreads onto your land. Birketts has previously obtained injunctions for clients in such circumstances, requiring the neighbouring property to remove the Knotweed, before it spreads or causes damage.