In Arceneaux v. Howard, 633 So. 2d 207, 210 (La. App. 1st Cir. 1993) the plaintiff received a contusion to the head during a head-on collision at 30-35 mph. Mr. Arceneaux's seatbelt broke and his car was totally destroyed. The medical and lay testimony for causation was rebutted only by speculative opinions. Thus, the material facts were not genuinely in dispute. From those facts, the level of the impact would seem irrelevant.
As the force of impact in a collision lowers, and the seriousness of the injury rises, expert testimony becomes more relevant. An expert's commentary on speed, rate of acceleration, force of impact, and the correlation to injuries suffered as exemplified in reliable published studies would become an integral part of the defense or plaintiff's case. A plaintiff or a defendant cannot be deprived of their right to offer a reasonable presentation of issues by the rigid, artificial application of a jurisprudentially created aid for the proof of causation. Each particular case must be reviewed on its own facts.