Arscott & Ors v The Coal Authority & Anor

In private nuisance, the common enemy rule permits a landowner to protect land against floodwater, even where water that would otherwise enter is diverted to neighbouring land. The rule does not permit interference with an established watercourse, or the transfer of water already on, or about to enter, the defendant’s land. Works within those limits are prima facie natural and reasonable, subject to excess. Liability also requires reasonable foreseeability of the relevant causal chain. Exact mechanics need not be foreseeable, but some understanding of how the works would expose the claimant’s land is required. The Human Rights Act 1998 did not apply retrospectively to the events, and the rule was in principle compatible with Article 8 and Article 1 of the First Protocol.

Exceptional rainfall on 22/23 October 1998 caused the River Taff to overtop its banks at Aberfan. In the 1970s, spoil had been used to raise Grove Fields by 10 to 12 feet. The respondents accepted at trial that the infilling was a material cause of flooding to the homes of 32 appellants.

Royce J dismissed the appellants’ private nuisance claims. He applied the common enemy rule and alternatively held that the relevant flood damage was not reasonably foreseeable when the works were carried out. The appellants appealed, arguing that the rule did not apply, that foreseeability was established, and that the rule required modification in light of Convention rights. The central issues were the scope of the common enemy rule and the foreseeability of the causal link between the infilling and the flooding inside the appellants’ homes.

Lord Justice Laws gave the leading judgment. Lady Justice Arden and Lord Justice Tuckey agreed. The appeal was dismissed.

1. General nuisance principles. Private nuisance requires a balance between an occupier’s use of land and the neighbour’s right not to suffer interference. A natural or ordinary use is generally protected unless its quality or extent is unreasonable. A non-natural use involving the escape of a dangerous thing may engage the rule in Rylands v Fletcher, which the court treated as a species of nuisance. Reasonable foreseeability of damage is required in every category, including Rylands liability. These principles were drawn from Sedleigh-Denfield v O’Callaghan [1940] AC 880, Transco plc v Stockport MBC [2003] UKHL 61 and Cambridge Water Co v Eastern Counties [1994] 2 AC 264 (paras [24]–[31]).
2. Common enemy rule. The rule permits a landowner to erect defences against floodwater which would otherwise enter his land, even if the water is thereby diverted towards a neighbour. It does not permit interference with the established watercourse or alveus, nor the removal of water already on, or about to enter, the defendant’s land so as to cause greater damage to the neighbour. The limits illustrated by R v The Commissioners of Sewers for the Levels of Pagham (1828) 8 B & C 355, Hurdman v NE Ry Co (1878) 3 CPD 168 and Whalley v Lancs and Yorks Ry Co (1884) 13 QBD 131 help guarantee reasonable use. Grove Fields was a flood plain, not an alveus, and the additional height of the infill did not independently cause the damage. The rule therefore applied (paras [32]–[41], [48]–[52]).
3. Convention rights. The Human Rights Act 1998 was not in force when the flooding occurred, and no basis for retrospective application was established. Lord Justice Laws nevertheless stated, as a matter of principle and subject to exceptional cases, that the common enemy rule was compatible with Article 8 and Article 1 of the First Protocol because its limits strike a fair balance between competing interests (paras [42]–[46]).
4. Foreseeability. The precise mechanics of causation need not be foreseeable, but reasonable foreseeability requires some understanding of the chain of events by which the works would expose the appellants’ homes to flood damage. The issue was one of fact. The judge was entitled to rely on the absence of contemporary foresight, the failure to attribute the similar 1979 flood to the infilling, and the later need for sophisticated expert modelling. The Court of Appeal would not interfere absent an error in reasoning or a misapprehension of material evidence. The finding against foreseeability was therefore sustainable (paras [54]–[63]).
5. The appellants’ landlord argument added nothing to the rights conferred by their leases, and no public-law claim was advanced. The appeal was dismissed, with the appellants ordered to pay the respondents’ costs on the standard basis (paras [51], [64]–[66]).

1. Court of Appeal (Civil Division) — The appeal was dismissed, with costs on the standard basis. [2004] EWCA Civ 892.
2. High Court of Justice, Queen’s Bench Division — Royce J, sitting at Merthyr Tydfil, dismissed the appellants’ private nuisance claims on 16 July 2003.