Most of the cases looked at  in the Proving Things series have, inevitably, been first instance decisions.  To mark the 70th in the series we are looking at a Privy Council decision, Petroleum Company of Trinidad and Tobago Ltd v Ryan & Anor (Trinidad and Tobago) [2017] UKPC 30. It emphasises that, in the majority of cases, the burden remains with the claimant to establish causation.  The exceptions to this requirement are limited.



The claimants lived near to a redundant oil well. The well had been abandoned and plugged in 1943. The claimants suffered from  pulmonary fibrosis and reactive airways disease.  The attributed their symptoms to seepage from the well. The brought an action against the oil company.


The trial judge found that the seepage was minimal. Further he found that the medical evidence did not establish a link with the claimants’ ill health.


The Court of Appeal ( of Trinidad and Tobago) overturned the trial judge’s findings by a 2:1 majority. The majority held

“… the judge’s conclusions were affected by material errors and not supported by the evidence. For this purpose he conducted a detailed examination of the judgment and the evidence, written and oral, to which it will be necessary to return below. He held that the claimants had proved on the balance of probabilities the medical basis of their complaints, and the causative link with hydrocarbon emissions for which the company was responsible. He also criticised the judge for placing too stringent a burden on the claimants, in circumstances where the evidence relating to the well and its environs lay within the control of the company, and accordingly they required “little affirmative evidence to establish a prima facie case of negligence which the [company] then had to rebut” (paras 23-24).”


In a concluding section (para 58ff), Smith JA discussed a possible alternative approach to the issue of causation in negligence, designed as he put it to “bridg[e] any alleged evidential gaps …” Since this did not form part of his decision on the appeal, it will be convenient to address it so far as necessary at the end of this judgment (paras 47-49 below).”


The Privy Council allowed the defendant’s appeal against the decision of the Court of Appeal.

  • There was no basis for drawing adverse inferences from apparent gaps in the defendant’s evidence. This “gap” had not been explored at trial and the defendant had never been given an opportunity to respond.

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.”

  • The Board also set aside the Court of Appeal’s decision that the defendant’s medical evidence had been discredited in cross-examination. The expert had not examined the claimants but relied on a literature search and his own expertise.

 “In the light of this review, the Board can find no support for Smith JA’s statement that Dr Seemungal’s evidence had been materially discredited in cross-examination. In the Board’s view he was also wrong to discount Dr Coombs’ evidence as based simply on the literature. His witness statement indicated that it was based on 27 years’ experience as a medical officer in the oil and gas industry in Trinidad and Tobago, during which time he had not found a link between hydrocarbon emissions and pulmonary fibrosis. As Mendonca JA pointed out (para 27), Dr Coombs’ evidence also highlighted the importance of looking beyond general terms such as hydrocarbons, and identifying the particular type of emissions which might be found in a crude oil environment, as opposed for example to a refinery complex. This was a point also touched on by the judge (see para 18 above).

46.              In summary, the Board is unable to accept that the judge’s findings on the medical evidence were undermined by his failure to take account of material parts of the evidence, or were otherwise open to challenge.”



Of particular interest is the Board’s response to a comment that a “more flexible” approach to causation could be adopted.  This submission was rejected by the Board.


“The alternative approach

  1.  As noted above, Smith JA discussed the possibility of a more flexible approach to the issue of causation on policy grounds, taking account of greater public awareness of environmental issues and the responsibilities of polluters. He reviewed the familiar line of House of Lords authorities on proof of causation in cases of competing causes for industrial diseases: Bonnington Castings Ltd v Wardlaw [1956] AC 613McGhee v National Coal Board [1973] 1 WLR 1Wilsher v Essex Area Health Authority [1988] 1 AC l 1074; Fairchild v Glenhaven Funeral Services Ltd [2002] UKHL 22[2003] 1 AC 32. Adapting the approach of these authorities, he thought that, even if the claimants’ evidence did not strictly satisfy the “but for” test of causation, 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” (para 69).

  2.  More specifically, he saw the case as analogous to Bonnington, 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. In the present case, as Smith JA put it (para 65):

“(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.”

  1.  Mr Tager does not question the application of the Bonnington line of authorities in this jurisdiction. However, as he submits, it has no possible application in the present case where no causative link between the claimants’ condition and gaseous emissions – guilty or innocent – had 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). For the reasons already discussed, the Board agrees that this premise is not supported by the evidence. In these circumstances, it agrees with Mendonca JA (para 44) that this line of authorities provides no assistance to the claimants, and no basis for adjusting the ordinary approach to causation in the present case.”