Under section 85(1) of the 1991 Act, a person commits an offence if he "causes or knowingly permits any poisonous, noxious or polluting matter or any solid waste matter to enter any controlled waters." Compliance with a discharge consent is a good defence.
The wording repeats the formulation in previous legislation, and the lead 1972 decision of the House of Lords in Alphacell Ltd v Woodward held that the drafting implied two distinct heads of liability - causing the entry of polluting matter, and knowingly permitting its entry.
The enforcing authority, now the Environment Agency, must choose the appropriate charge, but the critical legal distinction is that with the permitting offence some proof of knowledge on the defendant's part must be proved. In contrast, the offence of causing the entry is one of strict liability in that lack of awareness is no defence, though it may be reflected in any sentence imposed. As Lord Hoffman put it in the Empress Car case: "The notion of causing is present in both limbs: under the first limb what the defendant did must have caused the pollution, and under the second limb his omission must have caused it."
The Alphacell decision insisted that the notion of causation in the offence must be given a common sense meaning. But since that case there have been a large number of High Court and Appeal Court decisions exploring what is meant by "causing the entry" of polluting matter. Some of these appeared to suggest that there must be a "positive" act on the part of the defendant, and that where the pollution was caused, say, by the failure of control equipment this could not be an offence under the first limb. Similarly, where the actions of a third party such as a trespasser had caused the direct entry of the polluting matter, the defendant could argue that the chain of causation had been broken.
These decisions now have to be re-evaluated in the light of the House of Lords judgement in the Empress Car case. The company maintained a diesel storage tank on its premises, which drained directly into a river. Although there was a bund around the tank, the company had overridden this by fixing an extension pipe to the tank outlet which connected to a drum outside the bund. The tank outlet was governed by a tap which had no lock.
In 1995, someone opened the tap, allowing the full contents of the tank to run into the drum, which overflowed into the yard and drained into the river.
The person who opened the tap was never identified. It could have been an employee or, since there had been local opposition to the company's business, an act of sabotage may have been involved.
Nevertheless, the company was charged with causing the entry of polluting matter into the river. It was convicted by local magistrates and lost an appeal to the Crown Court on the grounds that it had brought the diesel onto the site and had failed to take adequate preventative measures, such as fitting a lock on the tap and ensuring the integrity of the bund.
On appeal, the Divisional Court held that, despite the intervening act of a stranger, the Crown Court was still entitled on the facts to find that Empress Car had caused the pollution. But it agreed that the case law was confusing, and certified that there was a point of law of general public importance for the House of Lords to consider.
The House of Lords agreed that the first limb of the section 85 offence required there to be some positive act on the part of the company - but the critical question was what counted as a positive act.
Earlier case law, such as that of the Divisional Court in the 1992 case of Wychavon District Council v National Rivers Authority (ENDS Report 213, p 39 ), held that the failure to maintain a sewerage system which resulted in sewage overflows into a river could not amount to a positive act. But in Lord Hoffman's opinion, such decisions "take far too restrictive a view of the requirement that the defendant must have done something. They seem to require that his positive act should not have been in some sense the immediate cause of the escape. But the Act contains no such requirement. It only requires a finding that something which the defendant did caused the pollution."
Although the House of Lords reaffirmed that common sense notions of causality must apply, Lord Hoffman emphasised that answers to questions of causation would differ according to the purpose for which the question was asked.
Lord Hoffman drew the analogy of the owner of a car who left his radio in overnight. A thief breaks the window to steal the radio and in law would be considered to have caused the damage to the car, and he could not argue that it was the owner's carelessness that had caused the damage. But if this had been the third such occurrence in a year, a common sense, non-legal approach might suggest that it was the owner's failure to take reasonable care of his possessions that had also caused the damage and the loss of his radio.
Both approaches were correct in their own terms. In the case of a prosecution under section 85, it was therefore wrong to ask the question "What caused the pollution?" and there might be a number of different answers to that question. Instead, one had solely to consider "Did the defendant cause the pollution?"
When it came to questions of the acts of third parties or the influence of natural forces, there were situations where both as a matter of common sense and the application of legal rules there were duties to take precautions to prevent losses being caused by external events. But before considering questions of causation, it was necessary first to consider the purpose and scope of the rule in question to determine whether it imposed a duty to require one to guard against the deliberate acts of third parties or the operation of natural forces. This question was not one of common sense but one of law, and in the present case one of statutory construction.
It was clear that Parliament had imposed a strict liability for the first limb of the offence "in the interests of protecting controlled waters from pollution." Lord Hoffman agreed with statements in the Alphacell judgements that not every act of a third party could be said to interrupt the chain of causation, and to the extent that other cases such as Impress (Worcester) v Rees in 1971 suggested that they did they were wrongly decided.
Although liability under the first limb of the section 85 offence was strict, "it is not an absolute liability in the sense that all that has to be shown is that the polluting matter escaped from the defendant's land, irrespective of how this happened. It must still be possible to say that the defendant caused the pollution."
Some of the subsequent case law dealing with intervening actions of third parties had employed the test of foreseeability, asking whether the defendant could reasonably have foreseen what took place before he could be said to have caused the pollution. But Lord Hoffman was unhappy with the use of such language: "Foreseeability is not a criterion for deciding whether a person caused something or not. People often cause things which they could not have foreseen."
In his view, the true common sense distinction was between acts and events which were generally a normal and familiar fact of life, and those which were abnormal or extraordinary. Acts and events which were familiar in that sense would often be foreseeable, but foreseeability was not strictly a necessary element.
In this context, there was nothing extraordinary about leaky pipes, people putting substances unlawfully into the sewerage system, or ordinary vandalism. On the other hand, in the example given by Lord Hoffman, a terrorist attack which damaged a defendant's works and gave rise to pollution "would be something so unusual that one would not regard the defendant's conduct as having caused the escape at all."
The same distinction could be applied to natural events. In the Alphacell case, falling leaves and vegetation had blocked the defendant's pumps, causing an overflow, but the House of Lords held that they had still caused the pollution in that there had been no abnormal weather conditions but precisely what one would have expected in the autumn. The situation would have been different if there had been some extraordinary natural event or "Act of God".
Lord Hoffman ended his judgement by summarising the key principles to be applied in the case of a charge under section 85. These are now likely to be widely used by magistrates and other courts dealing with water pollution offences.
First, the prosecution must be asked to identify what it says the defendant did to cause the pollution. If he cannot be said to have done anything then the prosecution must fail, although the circumstances might still warrant a charge of knowingly permitting the pollution. But the prosecution need not prove that what the defendant did was the immediate cause of the pollution - maintaining tanks, lagoons or sewerage systems were all doing something, even if the immediate cause was something else.
Courts must then consider whether what the prosecution alleged the defendant did could be said to have caused the pollution, and must not be diverted by questions such as: "What was the cause of the pollution?" or "Did something else cause the pollution?"
Where the actual escape was also caused by the act of a third party or a natural event, courts must consider whether this should be regarded as a normal fact of life or something extraordinary. "If it was in the general run of things a matter of ordinary occurrence, it will not negative the causal effect of the defendant's acts even if it was not foreseeable that it would happen to that particular defendant or take that particular form. It if can be regarded as something extraordinary it will be open to justices to hold that the defendant did not cause the pollution."
This distinction between ordinary and extraordinary was one of fact and degree which courts must apply with common sense and knowledge of what happens in the area. On the facts of the Empress Car case, the House of Lords felt that there was ample evidence to entitle the courts below to find that the company had caused the pollution.
The decision clearly throws light on what has proved a difficult area of law, and imposes greater duties on industries and sewerage undertakers to take appropriate preventative steps to guard against the actions of third parties, equipment failure, or natural events such as storm damage.
Lord Hoffman's analysis of what is implied by causation may be of relevance to other areas of environmental law, but the decision is strictly confined to section 85 water pollution offences. Many pollution offences are now contained in the Environmental Protection Act 1990, but these are often drafted in differing terms reflecting their distinct historical origins.
The key offences concerning waste disposal, for example, use the term "cause or knowingly permit" but the term "knowingly" also qualifies the causation limb, making the distinction of less critical importance. However, there appears to be little rational justification for maintaining such a distinction between the water and waste regimes.
The offences concerning integrated pollution control, in contrast, do not use the language of causation or permitting, but are directly related to operating without or in breach of an authorisation. The statutory nuisance provisions of Part III of the 1990 Act employ different terminology and place liability on the person "responsible" for the nuisance or in some cases the owner or occupier of the land in question.
The opportunity was taken in the Environment Act 1995 to introduce greater consistency across the enforcement provisions of the different regimes, but it may be that the time has come for a more detailed analysis of the rationale behind the conceptual distinctions that still exist.