Davies v Bridgend County Borough Council [2024] UKSC 15

Japanese Knotweed spread from council land to claimant’s property before any breach of duty arose. The claimant sought damages for residual diminution in property value. The Supreme Court held the diminution predated the breach, failing the ‘but for’ causation test, and allowed the council’s appeal.

Facts

The claimant owned a terraced house at 10 Dinam Street, Nant-y-moel, Bridgend, Wales, adjoining land owned by Bridgend County Borough Council. Japanese Knotweed (JKW) growing on the council’s land encroached onto the claimant’s land at a date ‘well before 2004’. The claimant purchased the property in 2004, already affected by JKW. An actionable private nuisance arose in 2013 when the defendant was, or ought to have been, aware of the risk of damage from JKW and failed to implement a reasonable treatment programme. The defendant did not implement effective treatment until 2018, creating a period of continuing breach from 2013 to 2018.

Claim for Damages

The claimant sought £4,900 for residual diminution in property value existing despite JKW treatment. Expert evidence stated that stigma in the property market, fuelled by media coverage, caused the diminution even after treatment because JKW rhizomes remained in the soil and the property would require disclosure on resale.

Issues

The central issue was one of causation: whether the residual diminution in value was caused by the defendant’s breach of duty in private nuisance between 2013 and 2018, or whether it had occurred prior to the breach due to the original non-actionable encroachment.

Judgment

The ‘But For’ Test

Lord Stephens, delivering the lead judgment, applied the standard ‘but for’ test for factual causation. He stated:

The starting point is that the decision of the House of Lords in Delaware is not authority for the proposition that diminution in market value is recoverable, regardless as to whether the diminution occurred prior to the defendant’s breach of duty.

Applying the test, Lord Stephens concluded:

In that context the answer to the ‘but for’ question is simply that the diminution in value had occurred long before any breach by the defendant of the relevant duty in private nuisance first occurred in 2013. Accordingly, the application of the ‘but for’ test in this case eliminates the defendant’s subsequent breach of duty as a causative factor.

Rejection of Delaware Analogy

The Court of Appeal had relied on Delaware Mansions Ltd v Westminster City Council to conclude the harm was caused by the continuing breach. However, the Supreme Court held that Delaware concerned recovery of reasonable costs incurred in abating a continuing nuisance, not diminution in market value predating the breach.

Delaware establishes that where there is a continuing nuisance the claimant is entitled, in appropriate circumstances, to abate the nuisance and to recover the reasonable costs incurred in doing so. However, a loss representing a diminution in market value is not an aspect of reasonable costs incurred in abating a continuing nuisance.

Concurring Judgment

Lord Burrows concurred, emphasising the application of factual causation principles. He drew an analogy with Performance Cars Ltd v Abraham, stating:

Applying the ‘but for’ test to the facts of this case, the breach of duty from 2013 did not factually cause the residual diminution in value of the land. The claimant has not proved that the residual diminution in value would not have been suffered but for the breach of duty.

Rejection of Claimant’s Further Issue

The claimant’s alternative argument that stigma decreases over time, and earlier treatment would have reduced diminution, was rejected as it was neither pleaded nor supported by evidence.

Implications

This case clarifies the application of causation principles in private nuisance claims involving natural hazards like JKW. A claimant cannot recover damages for loss that predated the defendant’s breach of duty, even where there is a continuing nuisance. The decision distinguishes between recoverable costs of abating a nuisance and irrecoverable pre-existing diminution in value. It has significant implications for landowners, including Network Rail, who intervened in the proceedings.

Verdict: Appeal allowed. No damages awarded. The residual diminution in value of the claimant’s land occurred prior to and was not caused by the defendant’s breach of duty in private nuisance.

Source: Davies v Bridgend County Borough Council [2024] UKSC 15