Holtz v. Holder
Arizona Supreme Court
418 P.2d 584 (1966)
Cynthia Holtz (plaintiff) collided with James Holder's (defendant) car at a merging lane and, minutes later while sitting stationary after that first crash, was struck again by a Carnation Milk (defendant) truck; her doctor testified it was impossible to determine which injuries came from which collision. The trial court instructed the jury it could not rule for Holtz unless it could determine which defendant caused which injuries, rejecting Holtz's proposed instruction allowing joint and several liability if the injuries couldn't be apportioned, and the jury found for the defendants.
Whether multiple tortfeasors who injure a plaintiff through successive incidents may be held jointly and severally liable for the entire injury when it is impossible to determine how much harm each tortfeasor caused.