Out-Law News 1 min. read

Council not liable for Japanese knotweed damage

A recent UK Supreme Court ruling clearly sets out the parameters of the law of private nuisance claims in the context of Japanese knotweed, clarifying the nature and extent of evidence needed to enable a claim to succeed, an expert has said.

The Supreme Court, in the case of Davies v Bridgend County Borough Council, ruled that a party was not entitled to damages despite Japanese knotweed spreading across their property from council-owned land, which the claimant, Mr Davies, argued reduced the value of his home. This was because there was no evidence before the trial judge that the nuisance which occurred between 2013 and 2018 had increased or materially contributed to the diminution in value of Davies’s land. Japanese knotweed first spread to Davies’s land sometime before 2004, when this was not an actionable private nuisance. The damage had already been done before the council could be said to be liable in private nuisance, and Davies, therefore failed the so-called ‘but for’ causation test. He therefore received no damages.

Ian Morgan, property disputes expert at Pinsent Masons said the decision “is relevant to a huge variety of property stakeholders, particularly owners of large swathes of unoccupied land, such as developers, railways and canals and the owners of neighbouring property.  It will also be of more general interest in the context of a so-called ‘continuing nuisance’ which was only last before the UK Supreme court in 2023.”

Japanese knotweed can in some cases result in structural damage and for this reason has historically been viewed as a problem for property transactions because it can be difficult to eradicate entirely and can easily spread.

“This had led lenders and insurers to take a cautious approach, yet more recently, thinking has evolved to take a more holistic view of the risk, with the Royal Institution of Chartered Surveyors publishing a professional standard in 2022, which talks of the need to ‘rebalance perceptions’,” said Morgan.

The court ruled that the knotweed had already spread onto Davies’s property from council-owned land well before the nuisance claims were raised. While it was accepted that Bridgend council had failed to treat the problem quickly, Japanese knotweed had already been present and the so-called “but for” causal test could not be satisfied. As such, no damages were awarded.

Morgan said: “While this case may bring a degree of comfort that evidence of loss will need to be provided, which will often be more difficult in practice where the infestation is historic, the Supreme Court has not completely closed the door on private nuisance claims where there is Japanese knotweed infestation. Furthermore, it is important to remember that Japanese knotweed can bring with it  various obligations such as aspects of environmental law, including potential criminal offences, and, so, it is important to take measures ideally to prevent the infection of land with Japanese knotweed in the first place and secondly to take proper advice quickly on how best to identify and then manage and mitigate the risks if you suspect it is either growing near to your property or has in fact encroached onto your land.”

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