(concurring specially):
I concur in the result reached by the majority but for the reasons which the trial court ascribed. The district judge held that under I.C. 49-1404(1) that the negligence of the operator of the vehicle was “imputed to the owner for all purposes of civil damages.” Thus, the admitted negligence of the driver was imputed to the plaintiffs’ decedent under § 49-1404(1) and constituted contributory negligence. This Court said as much in Bush v. Oliver, 86 Idaho 380, 386 P.2d 967 (1963). In that case, the Court quoted from Milgate v. Wraith, 19 Cal.2d 297, 121 P.2d 10 (1942), as follows:
“ ‘Appellant contends that the above-quoted section should be so construed as to limit the imputation of negligence to actions by third persons against the owner. Whatever might have been the proper construction prior to the 1937 amendment, it is now clear that since the passage of that amendment, said section is not susceptible of such construction. The phrase “the negligence of such person shall be imputed to the owner for all purposes of civil damages” can be interpreted in no other sense than to include actions by the owner against third persons. Indeed, that was undoubtedly the very purpose of the amendment. If the section were not so interpreted, the added portion would be meaningless, * * *.’ ” (Emphasis added). 86 Idaho at 384-385, 386 P.2d at 970.
The Court in the Bush case then concluded by stating:
“We conclude that the last phrase of I.C. § 49-1404(1), heretofore quoted, must be interpreted to include actions by or against third persons and not actions by the owner against the driver.” (Emphasis added). 86 Idaho at 386, 386 P.2d at 971.
The trial court correctly followed I.C. § 49-1404(1) as construed in the Bush case. I would affirm the judgment of the trial court for that reason.
However, it is necessary to comment on certain statements expressed in the majority opinion with which I strongly disagree. The majority opinion, while assuming that the defendants were negligent for failure to properly put up warning signs, nevertheless concludes that “[t]o find that Mansfield’s failure to erect yellow, four-foot by four-foot warning signs, was an actual cause of Ostergar’s death would require a finding that those signs would have provided more notice of the blocked highway than did the obvious blockage itself. This *533we cannot do.” By weighing the evidence and deciding that a vehicle stopped in the roadway at a construction site necessarily provides more notice of the need to stop than would appropriately placed warning signs farther down the road, the majority has invaded the province of the jury and usurped their factfinding function. If it is necessary to decide whether properly placed warning signs would have provided more notice of the blocked highway than did the blockage itself, the jury, not the trial court upon motion for summary judgment or this Court upon appeal, should decide that issue of fact. It is the jury’s responsibility to determine if there was negligence and, if so, whether that negligence actually caused the injuries involved.
Aside from my objections concerning the usurpation of the jurors’ traditional functions, I further believe the quoted language displays a lack of understanding of the concept of causation in negligence actions. The majority opinion states, “To find that Mansfield’s failure to erect yellow, four-foot by four-foot warning signs, was an actual cause of Ostergar’s death would require a finding that those signs would have provided more notice of the blocked highway than did the obvious blockage itself. This we cannot do.” What that phrase says is that negligence, in order to be actionable, must constitute more than 50% of the proximate cause of the accident. I don’t understand that to be the law. The majority earlier said that negligence is an actual cause of an injury when it is a substantial factor in bringing the injury about. This latter statement is accurate. Prosser, Law of Torts, p. 240 (4th ed. 1971) ; Restatement (2d) of Torts, §§ 431, 433 (1965). But taking the two statements together, the majority is saying that negligence is not a substantial factor unless it is more than 50% of the cause of the accident. I know of no authority supporting that position, and the majority has cited none. In any event, such a finding is an invasion of the province of the jury to find the facts. As stated in Prosser, Law of Torts, at p. 240:
“The defendant’s conduct is a cause of the event if it was a material element and a substantial factor in bringing' it about. Whether it was such a substantial factor is for the jury to determine, unless the issue is so clear that reasonable men could not differ. It has been considered that ‘substantial factor’ is a phrase sufficiently intelligible to the layman to furnish an adequate guide in instructions to the jury, and that it is neither possible nor desirable to reduce it to any lower terms. As applied to the fact of causation alone, no better test has been devised.”
The plaintiff has shown sufficient facts from which reasonable men could conclude that there were two independent negligent acts, both of which were an actual cause of the accident. The first was the failure of the contractor to erect the appropriate signs, and the second was the negligence of the driver of the Ostergar vehicle in which the plaintiffs’ decedent, Mr. Ostergar, was riding. Had there been a third party who was injured by the collision, such as an occupant of the car which the Ostergar vehicle struck, the third party should certainly be able to proceed against either or both of these negligent joint tortfeasors, the driver or the contractor, and should be able to collect damages from either of them. However, the majority, in order to maintain consistency, would still have to say that the signs would not have provided any more notice than the third party’s car, and therefore hold that the negligence of the contractor in failing to put out the signs was not an actual cause of the accident. Thus, a third party would have no right of recovery against the contractor, one of the joint tortfeasors. Merely because the majority feels that the driver’s negligence contributed to the accident to a greater extent than the contractor’s negligence does not mean the contractor’s negligence could not be a cause of the accident. Yet this is the effect of the majority opinion, and if it becomes the law it would rewrite the law of joint tortfeasors and set dangerous precedent for the developing law of comparative negligence.