Proximate cause tends to be the least understood element of the elements of a negligence claim. It may be best to think of it as a catch-all: even with every other element satisfied, there might be philosophical or policy reasons to ask a plaintiff to show more. The “duty” element of negligence, as we have seen, has also served this role — a way of circumscribing liability through fiat, as a matter of law, and therefore early in a case. Proximate cause is harder to pin down; whether it has been met can become a jury issue when a judge thinks it’s not an easy call. (Indeed, in the celebrated Palsgraf case among this section’s readings, the dueling opinions differ on whether the hiccup found within the fact pattern is best categorized as one of duty (Cardozo) or proximate cause (Andrews)).
If proximate cause were to be encapsulated in a single word, it might be: fortuity. Sometimes only the barest fortuity, if any at all, ends up linking the other elements of negligence, and in those cases we stop to consider whether there should be liability. Our first case, Vosburg, saw the prospect of unanticipated major harm from a simple kick to the leg in a classroom. Fair to have the defendant pay all? The law’s answer tends to be yes, but the pause before affirming it is a pause around proximate cause.
For a clean example in which proximate cause really does preclude liability, suppose I’m speeding imprudently, and a falling boulder (one that could not be anticipated) strikes the car spontaneously from above, injuring my passenger. My negligence — represented by the speeding — was a but-for cause of the harm, since if I’d been going slower (or faster, for that matter), the boulder would have missed us. But it’s a mere fortuity that my unreasonable act caused the harm in question; the harm is not linked to the undue risk that makes my behavior a breach of the standard of care. Is it fair for me to have to pay for my passenger’s harm, if I wouldn’t be responsible if the boulder hit us when we were driving normally? The law’s answer tends to be no.
Proximate cause comes up when fortuity is at work, and the cases we review in this section seek patterns in the spectrum from Vosburg’s “eggshell plaintiff” rule to the no-liability outcome of the wayward boulder.
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