Supreme Court overturns Japanese Knotweed redress ruling

A landmark ruling on the affect of Japanese knotweed on property values has been overturned, which could have implications for home buyers and sellers affected by the invasive plan.

In February 2023, homeowner Marc Christopher Davies won a Court of Appeal cases against Bridgend Council after Japanese knotweed encroached into his property from council land.

He was awarded £4,900 for the diminution in value of his home in Bridgend, Wales, due to the stigma associated with knotweed.

However, Bridgend Council appealed and the case was heard in the Supreme Court, which this week ruled that he is not entitled to any compensation.

Lord Justice Stephens ruled that while Bridgend council had failed to tackle the knotweed until 2018, it had existed since 2013.

This meant knotweed had already been present for years before the issue was raised so it could be argued that the reduction in value couldn’t be avoided.

Commenting on the judgement, Nic Seal, founder of invasive plant specialists Environet said:  “The claimant is not now entitled to damages for diminution in the value of his property because the loss was deemed to have occurred prior to the Council’s breach of duty in 2013.

“But this judgement has clarified that any resultant diminution and/or remediation works necessitated after the breach of duty are recoverable.

“This judgment does not therefore mean that all future knotweed-related claims will fail, since most cases of knotweed encroachment will have occurred more recently. But it does highlight the critical importance of homeowners being alert to what is happening on adjoining land and putting a neighbouring landowner on notice where knotweed is at or near a boundary.

“With constructive knowledge of the problem, if the neighbour fails to act and encroachment occurs, then a nuisance claim including residual diminution may well succeed.

“I expect we may also see a rise in victims of encroachment demanding the method most likely to achieve eradication of knotweed, namely excavation, rather than settling for damages calculated on the sum of herbicide treatment cost and diminution, since the diminution element of their legal claim may now be less assured.”