Japanese knotweed: untying the knot on liability for "blight" ?

Davies v Bridgend County Borough Council [2024] UKSC 15

Did the breach cause the loss?

Summary

An owner of an investment property claimed damages for the reduction in the value of the property caused by the encroachment of Japanese knotweed from neighbouring land which had since been treated and eradicated.  Our previous article Davies v Bridgend (Court of Appeal) covered the Court of Appeal decision which held that damages representing diminution in value could be awarded  for nuisance.  The defendant appealed claiming that the claimed loss was not caused by the breach in question.

The facts

Mr Davies had bought the subject residential property for investment in 2004.   In 2019, Mr Davies notified Bridgend County Borough Council (the Council) that Japanese knotweed from their neighbouring land had encroached onto his property.  The lower courts had already determined that the Council had become or ought to have become aware of the Japanese knotweed in 2013 and from that point and until 2018 was in breach of its duty as a neighbour to treat the knotweed.   Mr Davies' was awarded damages of £4900 representing the "residual" diminution in value remaining even after the knotweed had been treated and eradicated.  

Point argued on appeal

The defendant Council appealed this award of damages on the ground that any diminution in value was suffered well before 2004 when, according to the expert evidence, the Japanese knotweed was introduced to the Claimant's land.    As there was no actual breach on the part of the Council until it knew or ought to have known in 2013, the breach postdated the loss and therefore did not cause it. There was no evidence that there was any increase in the original diminution in value when the breach occurred between 2013 and 2018.

The decision

The Supreme Court applied the "but for" test adopted to establish causation. So would the diminution in value have occurred “but for” the breach of duty of the Council between 2013 and 2018? The Supreme Court held that the diminution in value was suffered before the breach and so the breach did not cause the loss.   The appeal was therefore allowed and Mr Davies was not entitled to damages.

Our comments

Given the point in principle here, it is understandable why the case reached the Supreme Court despite the low level of damages claimed. The case demonstrates that judges do not always agree and that ultimately, it is the Supreme Court that has the last word.