Bill Dhariwal reviews a landmark ruling by the Supreme Court relating to Japanese Knotweed damages

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Don’t Delay with Japanese Knotweed claims - New ruling by the Supreme Court

A previous decision regarding the amount of damages due to a victim of Japanese knotweed encroachment has been overturned by the Supreme Court.

In February 2023, 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 due to the stigma associated with knotweed which may impact upon the value and deter any future sale of the property.

Following an appeal from the Court of Appeal to the Supreme Court it was held on 08 May 2024 that Mr Davies was not entitled to any compensation.  This was because although Mr Davies had established that Japanese knotweed had encroached upon his land which he was required to remedy in about 2018, it had been present on his land well before this date.  His right to pursue an action in private nuisance against the council arose from 2013 when the risks associated with this particular plant were publicly available.  Accordingly, as it had been present years before he raised any issues with the council, it was successfully argued that he had suffered no loss as the reduction in value could not be avoided.

The Supreme Court applied the “but for test” (known to all law students studying tort law).  This tests ask whether the diminution in value would have occurred “but for” the breach by the council in permitting the Japanese knotweed to encroach on Mr Davies’ land?  The court found that as the diminution in value had occurred long before the breach by the council there was no loss to Mr Davies.  

This landmark decision will have an impact on victims of Japanese knotweed encroachment who may not know be able to claim any diminution in value damages if the invasive plant was found to have been present many years before they gave notice or issued legal proceedings against their neighbours or the source of the infestation.

The decision confirms that the costs of remediation are still likely to be recoverable.  This may include excavation of the invasive plant or herbicide treatment.

The message from the Supreme Court is clear to victims of encroachment.  Any major delay is likely to result in your damages claim being severely curtailed.

Should you have any questions regarding claims relating to Japanese Knotweed, please do not hesitate to contact us on 01489 864 100 or

The above article does not constitute legal advice.