The petition for rehearing is denied. Such denial, however, is not to be taken as a complete approval of the instruction that the defendant must show "that the overturning of the car was the result of inevitable casualty which human foresight and care could not prevent, for the law holds it responsible for the slightest negligence, and will not hold it blameless except upon the most satisfactory proofs."
[2] The true rule is that where the accident is of such a character that it speaks for itself, as it did in this case, and raises a presumption of negligence, the defendant will not be held blameless except upon a showing either (1) of a satisfactory explanation of the accident, that is, an affirmative showing of a definite cause for the accident in which cause no element of negligence on the part of the defendant inheres, or (2) of such care in all possible respects as necessarily to lead to the conclusion that the accident could not have happened from want of care, but must have been due to some *Page 695 unpreventable cause, although the exact cause is unknown.[3] In the latter case, inasmuch as the process of reasoning is one of exclusion, the care shown must be satisfactory in the sense that it covers all causes which due care on the part of the defendant might have prevented. In the case of an accident to a passenger in the course of transportation by a railway company, the explanation or care shown, as the case may be, must be most satisfactory in the sense that the carrier is held to a very high degree of care.
[4] But the proof which is required of such explanation or care is a different matter from the explanation or care itself. The explanation or the care shown, if true, may be perfectly satisfactory. The proof of its truth may or may not be satisfactory. On this point the rule is the same as in the case of any other presumption which a defendant must meet, that is, he is not obliged to overcome the presumption by a preponderance of evidence, but it is sufficient for him to give such proof of the truth of his explanation or of his contention that he exercised due care in all particulars as to offset the presumption in the minds of the jury and produce a balance in their minds on the question of its truth. Throughout the plaintiff must prove his case by a preponderance of evidence. (See Haun v. Tally, ante, p. 585, [181 P. 80].)
The instruction in question was taken verbatim from Bonneau v. North Shore R. R. Co., 152 Cal. 406, [125 Am. St. Rep. 68,93 P. 106], where it was approved. An examination of that decision, however, shows that the criticism which the appellant there made of that particular instruction was not directed to the point that it required most satisfacory proof as distinguished from a satisfactory explanation or a showing of satisfactory care. The rule in regard to proof is discussed with reference to another instruction and is stated to be as above.
In the present case the instruction, while open to criticism in the particular indicated, could not have misled the jury when considered in connection with the other instructions given as to the effect of a presumption and the requirement that the plaintiff prove his case by a preponderance of evidence.
All the Justices concurred, except Lennon, J., who was absent. *Page 696