(And anybody else who cares to participate)
The assumption around here is that Slaw is the most widely read, or at least one of the most widely read law blogs, amongst lawyers (academic and practicing), judges, and others associated with the profession. I’m going to (try to) put that to the test.
As some of you know, my particular (legal) research interest is factual causation in tort, particularly negligence. I’ve described that interest, on occasion, as the search for the “f” in actual cause.
I pose this question for those of you involved in civil litigation.
Are you prepared to accept that sufficiency rather than necessity is the accurate explanation for factual causation?
That sufficiency doesn’t mean the negligence “all by itself” but means, in substance, “sufficient when added to the background conditions which, together with the negligence” produce a cause.
That the reason why the necessity test you’re accustomed to using in most cases – the but-for test – works is that the parameters of the case are defined, going in, so that necessity is equivalent to sufficiency?
I’m asking you to accept
- 1. that negligence may be a cause of harm, on a more likely than not basis, even if the negligence is not necessaryfor the occurrence of the harm, so long as it is sufficient for the occurrence of the harm;
- 2. that there is another configuration of facts, which does not include the negligence, which is also sufficient to cause the harm may mean, but does not necessarily mean, that the configuration including the negligence is not a factual cause.
Without giving examples, what this means is that
1. in some cases, a factual cause will be both necessary and sufficient
2. in some cases, a factual cause will be sufficient but not necessary
3. in some cases, a factual cause will be NEITHER necessary nor sufficient. (Trust me on this one, for now. If you accept 1 and 2, 3 necessarily follows – readily enough, I think – and in any event it’s clearly explained with an example. An example is on the next screen.)
I, of course, don’t expect responses from judges who read this blog, but perhaps someone will say something in reasons for judgment that will hint that the judge has considered the issue, maybe even because the judge read something here.
The example of a cause which is neither necessary nor sufficient. (I’m not the originator of the example. It’s well known in more academic circles. One scholar has called it the “too little and too much”. The quotation comes from his text: Wright, Cases and Materials on Tort – it’s a U.S. text)
Assume three drops of poison are necessary and sufficient (in conjunction with other “background” conditions) for killing someone. Emily and three other people each put one drop into a cup which Paul drinks. Paul dies. … [E]each drop of poison was a cause of … Paul’s death, since each drop was a necessary element of a sufficient set of actual antecedent conditions that includes only two of the other drops. The extra (fourth) drop not in the set does not preempt that set’s causal effect by eliminating one of the “background” conditions that also is necessary for the actual sufficiency of the set, but rather duplicates or reinforces the causal effect of the sufficient set.
The underlying assumption is that the poison mixes with the liquid in the cup so it’s not possible to separate the individual does. The drops of poison simply combine into a larger amount of poison, amounting to more than 3 or more “drops” worth. There’s no chemical difference in the various drops.
Was the conduct of any one of the people necessary? No, because taking his or her drop out still leaves enough to poison. (Addendum: May 24 – this use of “necessary” is diferent from the but-for use of “necessary” because, there, the negligence is necessary for the harm to occur at all. Here, it’s necessary only for one configuration of of events sufficient to cause the harm.)
Was the conduct of any one of the people sufficient? No, because we need a total amount of poison equal to 3 or more drops.
And it’s not a case of the straw breaking the camels back. We don’t have a case where P drank from the cup after the 3rd drop.
If you’ve come this far, and care to, tell whether you agree with the statements that follow after the hypothetical.
- S Co. rents a car to D. S Co. hasn’t maintained the car properly, so the brakes will fail after a number of usages. D doesn’t know that. D drives away. The brakes seem to be working. D is driving within the speed limit. For the last 1/2 mile or so he hasn’t needed to apply the brakes. The last time D used them they worked properly. For whatever reason D stops paying proper attention to what’s ahead of him. As a result, he doesn’t see P’s car come out of the side road onto the highway. By the time D looks up and he sees P’s car, it is too late to brake. D’s car strikes P car. An investigation afterwards shows that the brakes on D’s car had failed about 1/2 mile earlier because the brake line broke, allowing the brake fluid to escape.
The questions are:
- 1. Do you consider D’s failure to apply the brakes a factual cause of the accident?
- 2. Do you consider S’s failure to maintain the brakes a factual cause of the accident?
- 3. Do you consider S’s giving the defective vehicle to D a cause of the accident.
P’s conduct in pulling out in front of D was, obviously, a factual cause so you don’t need to mention that unless you somehow think it relevant.
P.S. May 23/10: For any one who is interested, west of here (in the physical world) and merely elsewhere in the datasphere (?) – blogsphere(?) – on the University of Alberta Facultyof Law, Faculty Blog - I have been and will be writing about the substantive law, and some of the cases, dealing with factual causation issues. Getting the law right is important for any number of good reasons, including that it does make a practical difference to the both the public and internally even if (formally) appeals are from the result and not the reasons for the result.