Since the disease was caused by the totality of the toxic material inhaled, the relevant question was whether the particles from the swing grinders made any material contribution to the whole. (emphasis added)
The Board does not share the view of the Court of Appeal that the case involved a departure from the “but-for” test. The judge concluded that the totality of the claimant’s weakened condition caused the harm. If so, “but-for” causation was established. (emphasis added)
On the broader question of whether the Judicial Committee was correct to say that the hospital board’s negligence made a material contribution to the harm, I can see what Sarah is arguing, but the court does say at [41]-[42] that the harm was caused by a gradual process over a period of time, and the hospital’s carelessness had contributed to the total lapse of time. The evidence doesn’t seem to reveal whether or not all the harm had been done before the bit the hospital was responsible for. I guess on balance the court decided to accept the Court of Appeal’s view on that issue.
Still, as I say, good to see some clarification of “material contribution” and Bennington.
Regards (and Happy Australia Day to colleagues who celebrate!)
Neil
Acting Assistant Dean, Teaching and Learning
Faculty of Business and Law
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Date: Tuesday, 26 January 2016 at 2:34 PM
To: Sarah Green <sarah.green@st-hildas.ox.ac.uk>, "obligations@uwo.ca" <obligations@uwo.ca>
Subject: Re: Causation in the Privy Council
I was not seeking to defend the doubling-the-risk criterion. At least cases where the evidence of the pertinent risk is of an epidemiological or purely statistical character there are indeed problems with dtr. My point was just that the tiny-risk argument had little to do with the whether dtr was an acceptable approach to causation.
On the question of whether the defendant fell below the standard of care the tiny-risk argument is important. When we first hear that the defendant doubled the risk of some harm befalling the plaintiff we may be inclined to think that the defendant's behaviour was unreasonable. But when we learn that the risk doubled from one in a million to two in a million we may want to rethink that inclination.
But when it comes to causation, where it has already been found that the defendant's behaviour was unreasonable vis-a-vis the plaintiff, and where the risk has already materialized, then it seems to me that the tiny-risk argument has little to do with the
matter, or at least little to do with whether dtr is a good approach.
Sent: January 25, 2016 16:17
To: obligations@uwo.ca
Subject: Causation in the Privy Council
True – it is not a particularly convincing way of putting the argument, but the point is nevertheless an important one.
There are two principal reasons why the DTR test is not, without more, an appropriate device for calculating probability of causation. The first is that the relative ‘risk’ on which it is based is not in any technical sense a risk at all, but merely a measure of incidence over a defined population. To treat it as substitutive for probability, therefore, is to confuse two distinct concepts, with potentially adverse consequences for the causal inquiry.
The second reason is that the result reached by the relative risk calculation involved gives a ‘net result’. That is, it tells us how many extra cases of a disease are caused by the factor being tested. It does not, therefore, include those cases in which the adverse outcome would have happened anyway, just not when it did. In other words, it only identifies cases which would never otherwise have happened, and does not account for those which the factor merely accelerated. So, the DTR test and the measures on which it relies can underestimate a factor’s effect on a population. What it cannot do, however, is overestimate that effect.
The conclusion, therefore, that the incidence of injury has been doubled by the factor being tested amounts to a single indication that there might exist a statistical association between that factor and the injury. This is not, however, the same thing as establishing on the balance of probabilities that the factor caused the injury: such a statistic is just one component of the range of evidence on which a court should reach its decision, since it tells us nothing about what happened in any particular case.
Best,
Sarah
From: Vaughan Black [mailto:Vaughan.Black@Dal.Ca]
Sent: 25 January 2016 19:21
To: Sarah Green <sarah.green@st-hildas.ox.ac.uk>; obligations@uwo.ca
Subject: Re: Causation in the Privy Council
The argument that the doubling-the-risk test should be rejected because "a doubled tiny risk is still very small" is not especially convincing. It is true that if the defendant's actions increase the risk of the claimant suffering harm H from one in a million to three in a million that may not seem like a big deal. And it may be a reason for concluding that the defendant has not fallen below the standard of care. But if that the defendant has fallen below the standard of care and if the harm (the three in a million chance) has occurred, then why not conclude that, on a balance of probabilities, the defendant caused it?
From: Sarah Green <sarah.green@st-hildas.ox.ac.uk>
Sent: January 25, 2016 08:03
To: obligations@uwo.ca
Subject: Causation in the Privy Council
Dear colleagues,
In Williams v Bermuda Hospitals Board at https://www.jcpc.uk/cases/docs/jcpc-2014-0110-judgment.pdf, the PC grapples with the thorny issue of material contribution to injury.
The acknowledgement that the Court of Appeal in Bailey v MOD was wrong to describe material contribution to injury as an exception to the But For test is welcome, as is the recommendation that the doubling of the risk test should only ever be used with caution.
The dismissal of the Bermuda Hospital Board’s appeal , however, on facts which did not require a material contribution to injury analysis is not good news, particularly for medical practitioners and their insurers. An orthodox But For analysis along Barnett lines should have been applied, under which a different result would have been reached – the evidence (patchy thought it was) suggested that the claimant’s fate was sealed before the defendant contributed to the ongoing risk.
Best wishes,
Sarah
Sarah Green
Lord Hoffmann Fellow in Law
St Hilda's College
Oxford
OX4 1DY
01865 286661
https://www.law.ox.ac.uk/people/sarah-green