Staley, Chief Judge, and McLaughlin and Forman, Circuit Judges.
This is an automobile accident case with jurisdiction founded on diversity of citizenship and governed by the law of Pennsylvania, where the accident occurred. A trial by jury in the United States District Court for the Western District of Pennsylvania resulted in judgments in favor of the plaintiffs, Anthony T. Mihalic, Jr. and Kenneth C. Grafton against defendant Texaco, Incorporated (hereinafter Texaco) and in favor of Mr. Mihalic as a third-party defendant against third-party plaintiff Texaco. This is an appeal from an order of the District Court denying Texaco's motions for judgment n.o.v. and new trial principally on grounds that the trial judge did not properly charge the jury on the negligence law of Pennsylvania.
At approximately 6:00 p.m. on January 9, 1964, James C. Hoffman began a work assignment for his employer, Texaco, which entailed the hauling of five loads of aviation gasoline from Coraopolis, Pennsylvania to the Greater Pittsburgh Airport. This required Mr. Hoffman to ascend a one-and-one-half mile upgrade on Route 51, which, in this section, has two lanes and wide berms on both sides of the road. Mr. Hoffman testified that it rained during the first four trips but that he experienced neither slipperiness on the roads nor difficulty in negotiating the hill nor with his equipment; he admitted, however, knowledge of a forecast of dropping temperature. When at 11:30 or 11:45 p.m. he began his fifth trip, the weather had become snowy and colder, but Mr. Hoffman noticed no snow on the road at the bottom of the hill, though upon climbing further he saw that snow lay upon the highway in increasing amounts. At first, the tractor-trailer, with a gross weight of about 58,000 pounds carried through the snow, but about half-way up the incline, he felt some slipperiness and began using his "sanders" which deposit sand in front of the drive wheels of the tractor on control from the cab, and proceeded up the hill for five to eight minutes until the supply of sand was exhausted.
On cross examination Mr. Hoffman testified that he was unable to pull off upon certain paved areas along the road because they were blocked with automobiles, and that he thought it unwise to pull onto the berm, since the recent rain had made the berm so soft that a truck diverting upon it would "just get stuck," "with maybe only two wheels off the road." Thus when his sand ran out, he turned on his warning flashers and put chains on the drive wheels, noticing at this time that the highway was extremely slippery. With the chains in place he drove slowly up the hill and upon entering a left-hand curve he felt, and then through his rear view mirror, he saw, his trailer sliding into the downhill lane. Once more he turned on his warning lights and in order to avoid a "jackknife" which in his opinion might have blocked both lanes, he "followed" the slide of the trailer and backed across the left lane of the highway to the other side. He stated that he was able to get the trailer off the road but that the front end of the tractor stuck out into the downhill lane. Mr. Hoffman testified that he was taking flares from a box on the side of the trailer when he saw the car carrying Messrs. Mihalic and Grafton coming toward him.
Plaintiffs Grafton and Mihalic left an establishment known as Tony's Restaurant located 1000 to 1500 feet uphill from the tractor-trailer sometime after midnight. They had been driving on Route 51 at about 11:30, but the driver of their car, Mr. Mihalic, testified that it was not snowy or icy at that time. When they left Tony's Restaurant, however, it was snowing heavily, and Mr. Mihalic noticed that the roads were slippery. While descending in second gear at fifteen to twenty miles per hour with visibility impaired by the snowfall, Mr. Mihalic rounded a curve to the right and, according to his testimony, saw the lights from the tractor in the left lane and then saw the trailer moving across the right or downhill lane. When he first saw the tractor's lights, he judged that he was about 120 feet away, but he did not see the trailer until he was 30 feet away. His passenger, Mr. Grafton testified that when he first saw the tractor-trailer fifty or sixty feet away, the headlights were in the downhill lane and that he did not observe either part of the vehicle in motion. Mr. Mihalic did not remember putting on his brakes -- though Mr. Grafton thought that he did -- believed there was nothing he could do, and awaited the impact as his car slid into the tractor.
The appellant's first assignment of error is that the trial judge instructed the jury that a violation of Section 1004 of the Motor Vehicle Code of Pennsylvania,*fn1 requiring a vehicle to be driven on the right-hand side of the road, constitutes negligence per se, whereas the appellant contends that under Pennsylvania law such violation is merely prima facie evidence of negligence. The trial judge charged essentially as follows:
"So then, we have another provision of the code * * * that is that you shall drive your vehicle on the right-hand side of the highway, except in passing and overtaking.
"Any driver who fails to abide by the provisions of the code in the operation of his vehicle is guilty of negligence per se. * * *"
"Now, there are a couple of other rules in connection with a case of this kind. One of them is that a vehicle, an automobile, on the wrong side of the road is prima facie evidence of a driver's negligence. That is, the mere presence over there of the vehicle at any time -- that is, even if nobody saw it come over there, but it is there -- that is prima facie evidence of negligence.
"Now, if you would deliberately drive it over there or put it over there, as Mr. Hoffman said he did, then, of course, he is guilty of negligence under the law. Because, he is on the wrong side of the road. But, again, you see, unless it is the proximate cause of the accident and collision, it doesn't create liability."
Under Pennsylvania law, proof of a violation of Section 1004 is usually characterized as prima facie evidence of negligence.*fn2 We are less concerned, however, with the Latin terminology used in these jury instructions than with whether the process by which the jury was guided to its verdict corresponds with the process dictated by Pennsylvania law. Relevant cases indicate that proof of the basic fact of a violation of Section 1004 is "sufficient to carry the case to the jury," and will "justify a jury's finding the actor liable for the resultant injury."*fn3 This language alone does not support an instruction that proof of violation constitutes negligence as a matter of law, but in Matkevich v. Robertson,*fn4 the Pennsylvania Supreme Court indicated that such proof shifts a burden of justification to the defendant:
"Where, as here, the plaintiff is content to prove a collision as a result of the defendant's car being over on the wrong side of the road, the burden is on ...