This blog post is by James Beeton of 12 King’s Bench Walk.

The Privy Council decision in Petroleum Co of Trinidad and Tobago Ltd v Ryan and Anor [2017] UKPC 30 is based primarily on its own facts, but contains two broader points of interest for tort lawyers.

The first is the Privy Council’s refusal to draw an adverse inference or to shift the burden of proof to a defendant in circumstances where a ‘gap in the [defendant’s] evidence’ had not been explored with the witnesses at trial. This aspect of the decision highlights the importance of allowing another party the opportunity to explain its own failure to adduce potentially relevant evidence before inviting a court to draw an adverse inference in respect of the same.

The second is the Privy Council’s rejection of a sanguine approach to causation in cases involving environmental issues. Lord Carnwath (delivering judgment on behalf of the whole court) gives a concise reminder that Bonnington Castings Ltd v Wardlaw [1956] AC 613 is not authority for the general proposition that it may on occasion be appropriate to depart from the normal ‘but for’ test to causation. That decision involved a finding by the court that both guilty and innocent causative agents had as a matter of fact operated cumulatively to cause the claimant’s injury. Lord Carnwath’s decision on this point is consistent with the position adopted last year by the Privy Council in the case of Williams v Bermuda Hospitals Board [2016] UKPC 4.

Bonnington Castings does not therefore provide a basis for sidestepping the stringencies of the ‘but for’ test to causation where the court cannot first be satisfied of a link between the relevant agent(s) and the injury on standard causative principles.


The claimants, a father and daughter, had since 1994 lived 45 feet away from a disused oil well which was owned and formerly operated by the defendant. In 2006, the father was diagnosed with pulmonary fibrosis and the daughter with reactive airways disease. They attributed their conditions to emissions of hydrocarbon gases from the well and adjoining land under the defendant’s control and brought claims against the defendant in negligence and in nuisance.

The claims were dismissed by the High Court of Trinidad and Tobago. Rajkumar J accepted that the company had a duty to ensure that oil or other substances on land for which it was responsible did not emit gaseous emanations to such an extent as to pose a source of injury to adjoining landowners, and that it was sufficient for the claimants to show that those emissions made a material contribution to their complaints. He also accepted that there was some seepage of hydrocarbons from the area around the well before 2006. But he concluded that the amount was minimal, that the extent of any gaseous emissions was unquantified, and that in any event the medical evidence did not establish a link with the claimants’ ill health.

That decision was reversed by a majority in the Court of Appeal, which raised a number of criticisms of the judge’s decision.

Findings of Fact and the Burden of Proof

The Court of Appeal’s first concern was that Rajkumar J’s judgment contained material inconsistencies as to the existence of hydrocarbon emanations or natural seepage into the environment. That concern was rejected by the Privy Council: while there were some ‘inconsistencies of language in the judgment’, the substance was sufficiently consistent to be left undisturbed.

The Court of Appeal’s second concern arose from an apparent misunderstanding by Rajkumar J of evidence relating to air tests at the oil well. But Lord Carnwath considered that this was essentially a red herring since, whether or not there had been such a misunderstanding, it was ‘immaterial to the judge’s conclusions more generally’.

More interesting was the Court of Appeal’s third criticism of the judge, which related to his approach to the burden of proof in the circumstances of the case. Given the defendant’s admitted responsibility for the maintenance of the well, the Court of Appeal was of the view that the claimants had provided sufficient affirmative evidence (including their own evidence of seeing oil stains and smelling noxious odours) to establish a prima facie case of negligence against the defendant for failure to prevent seepage of oil and fumes, and so shift the burden to the company to rebut negligence. The Court of Appeal considered that the defendant had failed to adduce sufficient evidence to discharge the burden – noting in particular that it had failed to adduce evidence of its own historical tests relating to seepage levels.

However, Lord Carnwath was again unimpressed by that approach, noting that it would not be appropriate to draw adverse inferences or to reverse the burden of proof in respect of an issue that was not explored in detail with the witnesses at trial:

‘At this stage, however, it is difficult to draw any adverse inferences from this apparent gap in the company’s evidence. The time to have explored it would have been at trial, when the company would have been able to respond. For example, the company’s Chief Medical Officer, Dr Coombs, could have been asked to explain the medical concerns referred to in the application, and perhaps to produce any relevant internal reports. In the Board’s view, the mere absence of such evidence cannot be relied on as in itself providing any affirmative support for the claimants’ case, or as shifting the burden of proof to the company.’

Causation: A Flexible Approach?

The Court of Appeal also reversed the judge’s decision on medical causation on the basis that he had failed to take into account material parts of the expert medical evidence. However, Lord Carnwath again rejected the Court of Appeal’s conclusion in this respect and upheld the judge’s decision that no causative link between the gaseous emissions and the claimants’ ill health could be established.

Lord Carnwath then went on to consider a ‘more flexible’ approach to causation suggested by the Court of Appeal which was based ‘on policy grounds, taking account of greater public awareness of environmental issues and the responsibilities of polluters’ and which had been put forward as an alternative basis for their rejection of the judge’s conclusion on causation.

Smith JA (in the Court of Appeal) had considered that, by adapting the approach to causation in familiar authorities such as Bonnington Castings Ltd v Wardlaw [1956] AC 613, McGhee v National Coal Board [1973] 1 WLR 1, Wilsher v Essex Area Health Authority [1988] 1 AC 1074, and Fairchild v Glenhaven Funeral Services Ltd [2002] UKHL 22, causation could be made out even if the claimants’ evidence did not strictly satisfy the ‘but for’ test since there was a ‘sufficient substratum of evidence upon which a court could and should for policy reasons, draw inferences to bridge any such evidential gaps’.

He considered the case to be analogous to Bonnington Castings, where the employer was held responsible for disease of an employee caused by inhaling silica dust, only some of which was ‘guilty dust’ in the sense that it resulted from the employer’s failure to maintain dust-extraction equipment. His reasoning was that:

‘(a) There was exposure to natural oil and gas seepage for which the respondent may not have been responsible (innocent gas) or for which the respondent may have been responsible by the fact of FZ94 causing or aggravating the seepage (guilty gas). Further, there was also seepage of gas fumes from FZ94 and its environs before the 2006 remediation exercise which provoked the appellants’ medical conditions (guilty gas) and in the case of Mr Ryan, exposure at the tank farm many years earlier.

(b) There was no evidence of the proportion of guilty to innocent gas. Assuming that the evidence led did not satisfy the ‘but for’ test of causation, this is a case where one can and should draw the inference that the guilty gas was a contributory cause and like in Bonnington’s case, the respondent would be liable for the full extent to the loss.’

Lord Carnwath pointed out that the fatal difficulty with that proposition was that it had no possible application in circumstances where the causative link between the claimants’ conditions and the gaseous emissions (guilty or innocent) had not first been established:

‘Smith JA’s discussion proceeds on the erroneous premise that (in his words) the claimants “have proved that the gaseous emanations from FZ94 and its environs (were) at least a contributing cause of their injury” (para 63).’

Since that premise had already been rejected by the judge, the Bonnington Castings line of authority provided no basis for the adoption of a more sanguine approach to the issue of causation on policy grounds.

James Beeton Environment

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