It was the enlightened and famous judgement by Justice Cardozo in Wagner vs. International Railway Co. 43 which provided the rationale for allowing rescuers to recover even in cases where it could be argued that they were unforeseeable. In this case, a passenger was thrown from a train. The plaintiff in an attempt to rescue the passenger walked back along the train tracks to the point at which he thought his cousin would be. In attempting to effect the rescue, the plaintiff was injured. Justice Cardozo's judgement clearly and succinctly summarizes the issue of foreseeability as it relates to the law of rescuers.
Danger invites rescue.
The cry of distress is the summons to relief. The law does not ignore these reactions of the mind in tracing conduct to its consequences. It recognizes them as normal. It places their effects within the range of the natural and probable. The wrong that imperils life is a wrong to the imperiled victim.