In Peterson v. National Railroad Passenger Corporation, the Supreme Court affirmed a grant of summary judgment in a railroad negligence case. The incident occurred when an operator of a street sweeper machine feel asleep and his machine collided with the railroad tracks. The impact of the sweeper knocked the track several inches out of alignment. This malalignment caused derailment in which Peterson suffered injuries.
Plaintiffs argued and offered expert testimony that the railroad did not properly maintain the area of the track where the derailment occurred. They claimed that but for the railroad's negligence, the sweeper would not have misaligned the track to such a degree that the train would have derailed. The Supreme Court held that the expert testimony was insufficient to establish proximate cause:
None of the experts were willing to say that, had Respondents maintained the ballast in accordance with their own internal policies, such an impact would not have affected the rail to a degree that the train would have derailed. Moreover, none of the experts testified as to the amount of force necessary to knock an identical track with a six-inch ballast shoulder out of alignment. In fact, no testimony was presented that the track would maintain the necessary alignment had the sweeper jumped the crossties and struck the rail.
Accordingly, while evidence may exist that Respondents did not comply with their own internal safety policies, there is no evidence that this noncompliance caused the train to derail. Instead, the evidence overwhelmingly shows that the cause of derailment was the impact of the sweeper.