Network Rail Infrastructure Ltd v Williams & Anor

Private nuisance protects rights in land and the objective use and enjoyment of land. It does not protect a property's value merely as an investment or financial asset. Diminution in market value, without interference with land rights or amenity, is pure economic loss and is insufficient.

Physical damage is not invariably required. The concept of damage is elastic, and a sufficiently serious interference with the land's amenity or utility may complete the cause of action. Encroaching Japanese knotweed rhizomes constitute such an interference because they impose an immediate burden on development and affect an owner's ability fully to use and enjoy the land.

Japanese knotweed growing on Network Rail's land had spread beneath two neighbouring residential properties. The owners claimed in private nuisance. The recorder found no physical damage but held that the knotweed's effect on saleability and market value constituted an actionable interference with amenity. He awarded treatment costs, other losses and damages for residual diminution in value, but refused a mandatory injunction.

Network Rail appealed from the Cardiff County Court. It argued that diminution in value was pure economic loss and, alternatively, disputed causation of the residual loss. The owners relied on respondents' notices contending that encroachment was actionable without physical damage or that the presence of the rhizomes was itself damage.

The central questions were what kinds of damage support private nuisance and whether the rhizomes impaired the utility and amenity of the affected land.

1. The appeal was dismissed and the recorder's decision upheld, although for different reasons. The recorder had erred in treating diminution in market value, caused by lenders' caution, as an actionable loss of amenity. Private nuisance protects an owner's use and enjoyment of land as an incident of ownership or exclusive possession. It does not protect the property's value merely as an investment or financial asset. Extending it to such pure economic loss would radically reformulate the tort.

2. Private nuisance is a violation of property rights. Its conventional categories are examples rather than rigid compartments. The proposition that damage is always essential must be treated cautiously, and damage is an elastic concept. Physical damage is unnecessary where the nuisance consists of a sufficiently serious, objectively assessed interference with amenity. The assessment takes account of all the circumstances and the character of the locality.

3. The encroachment of Japanese knotweed rhizomes was actionable. The plant was a natural hazard whose presence imposed an immediate burden by making development more difficult and expensive, particularly because contaminated soil required special disposal. It therefore diminished the owners' ability fully to use and enjoy their land and constituted a classic interference with its amenity and utility. If damage was required, that diminished ability supplied it.

4. An occupier may incur liability through omission. Network Rail knew or ought to have known of the knotweed and its risks, yet failed to take reasonable measures to prevent the interference. The findings therefore satisfied the established principles concerning a landowner's responsibility for a known natural or man-made hazard.

5. The alternative challenge to the residual valuation evidence was misconceived, had not been raised below and did not justify a speculative and disproportionate remittal. Network Rail could not obtain a second opportunity to improve the case presented through its own expert.

Sharp and Leggatt LJJ agreed with the Master of the Rolls.

• Court of Appeal (Civil Division): The appeal was dismissed and the county court's decision was upheld on the alternative basis that encroaching Japanese knotweed rhizomes interfered with the utility and amenity of the owners' land: [2018] EWCA Civ 1514.
• Cardiff County Court: Mr Recorder Grubb found for both claimants in private nuisance, refused a mandatory injunction and awarded damages. He based liability on loss of amenity associated with reduced market value, while rejecting the encroachment claim because no physical damage had been proved. No citation is stated in the judgment.