In Tweedie v ICBC, the Plaintiff had gone out for a jog one morning. There were no witnesses to the accident that occurred, and the Plaintiff could not remember what had happened. The fact of the matter was, however, that she woke up with serious injuries. She thought she must have been hit by a car, and sued ICBC under the hit and provisions of Section 24 of the Insurance (Vehicle) Act. The lawyer for ICBC argued that there was no proof that a car had caused the collision, and, further, that there was no proof of negligence. The Court, relying only on circumstantial evidence, awarded the Plaintiff damages, and commented on the law of circumstantial evidence in the context of an injury claim arising out of a motor vehicle accident.
 The principles are well-established for assessing liability where the evidence is circumstantial, but it is still useful to refer to them. In the decision of the Supreme Court of Canada in Montreal Tramways Company v. Leveille,  S.C.R. 456, the Court considered the claim of injury, a deformity to an unborn child alleged to have been brought about as a result of the child’s mother falling while on the tramway. At p. 466, Mr. Justice Lamont considered the issue of whether there was evidence on which the jury could reasonably find the existence of a causal relationship between the accident to the mother and the deformity of the child’s feet, and said this:
The general principle in accordance with which in cases like the present the sufficiency of the evidence is to be determined was stated by Lord Chancellor Loreburn in Richard Evans & Co., Limited v. Astley,  A.C. 678 as follows:
It is, of course, impossible to lay down in words any scale or standard by which you can measure the degree of proof which will suffice to support a particular conclusion of fact. The applicant must prove his case. This does not mean that he must demonstrate his case. If the more probable conclusion is that for which he contends, and there is anything pointing to it, then there is evidence for a court to act upon. Any conclusion short of certainty may be miscalled conjecture or surmise but courts, like individuals, habitually act upon a balance of probabilities.
There was undoubtedly evidence to go to the jury that the mother’s accident was caused by the fault of the Company, and the jury’s finding on that point cannot be disturbed. That such fault caused the deformity of the child cannot, from the nature of things, be established by direct evidence. It may, however, be established by a presumption or inference drawn from facts proved to the satisfaction of the jury. These facts must be consistent one with the other and must furnish data from which the presumption can be reasonably drawn. It is not sufficient that the evidence affords material for a conjecture that the child’s deformity may have been due to the consequences of the mother’s accident. It must go further and be sufficient to justify a reasonable man in concluding, not as a mere guess or conjecture, but as a deduction from the evidence, that there is a reasonable probability that the deformity was due to such accident.
At p. 469, he referred to the decision of the House of Lords in Jones v. G.W. Rly. Co. (1930), 47 T.L.R. 39, in which the Court had to consider whether there was evidence on which a jury could properly find negligence on the part of the defendant’s servants which caused or contributed to the death of a husband of the first plaintiff. He quoted from the decision of Lord MacMillan:
The dividing line between conjecture and inference is often a very difficult one to draw. A conjecture may be plausible, but it is of no legal value, for its essence is that it is a mere guess. An inference in the legal sense, on the other hand, is a deduction from the evidence and if it is a reasonable deduction, it may have the validity of legal proof. The attribution of an occurrence to a cause is, I take it, always a matter of inference. The cogency of a legal inference of causation may vary in degree between practical certainty and reasonable probability. Where the coincidence of cause and effect is not a matter of actual observation there is necessarily a hiatus in the direct evidence, but this may be legitimately bridged by an inference from the facts actually observed and proved.
And then, on p. 474, after considering the difference in the jurisprudence in Quebec under the Civil Code and in the rest of Canada under the common law, he said:
… under either the French or English jurisprudence, the presumptions or inferences to be receivable as proof must be a deduction from established facts which produce a reasonable conviction in the mind that the allegation of which proof is required is probably true. That conviction may vary in degree between “practical certainty” and “reasonable probability”….
And at p. 475:
The question, however, is whether he instructed the jury sufficiently? In a case such as this it is, in my opinion, essential that the judge should instruct the jury that the presumption which they are entitled to admit as proof must not be a mere guess on their part, but must be a reasonable deduction from such facts as they shall find to be established by the evidence.
That is the standard which must be met here, where I am the trier of fact.
 In a decision of the British Columbia Court of Appeal, Plett v. Insurance Corporation of British Columbia, (1987), 12 B.C.L.R. (2d) 336, under the heading “Circumstantial evidence”, at p. 341, Mr. Justice Wallace said this:
In cases such as this, in which the evidence is circumstantial, inferences of negligence cannot be drawn unless there are positive proven facts from which such inferences can be made.
In Caswell v. Powell Duffryn Associated Collieries Ltd.,  A.C. 152,  All E.R. 722 (H.L.) a case concerning an industrial accident to a workman, Lord Wright stated at pp. 169-170 what is, in my respectful opinion, the correct approach to a case which turns solely on circumstantial evidence:
My Lords, the precise manner in which the accident occurred cannot be ascertained as the unfortunate young man was alone when he was killed. The Court therefore is left to inference or circumstantial evidence. Inference must be carefully distinguished from conjecture or speculation. There can be no inference unless there are objective facts from which to infer the other facts which it is sought to establish. In some cases the other facts can be inferred with as much practical certainty as if they had actually been observed. In other cases the inference does not go beyond reasonable probability. But if there are no positive proved facts from which the inference can be made, the method of inference fails and what is left is mere speculation or conjecture.
In the present case there are, I think, certain known facts which enable some inferences to be drawn. Beyond that point the method of inference stops and what is suggested is conjecture. It is not necessary to recapitulate the facts which have been fully stated by my noble and learned friend, Lord Atkin. I shall be content to state what I regard as proved by the method of inference, and reject what appears to be made to be a matter merely of conjecture