Were it not for Don Imus's outburst about the Rutgers women's basketball team and the ensuing brouhaha, NJ Governor Corzine almost certainly would not have been injured on the highway, because he would not have been on his way to a meeting with Imus and the team. Thus, when the red pickup swerved, the governor's vehicle would not have been run off the road (if indeed the red pickup would have swerved at all. Perhaps, per the butterfly effect, the driver of the pickup would have behaved differently in the alternative universe I'm positing). Does this make Imus responsible for Corzine's injuries? Of course not. As every 1st year law student knows, Imus was not the "proximate cause" of the auto accident. His remark was merely one of innumerable events that led to the governor's SUV being where it was when it was hit.
This conclusion does not turn in any way on the fact that Imus was engaged in legal (if offensive) behavior. Even if we suppose that Imus defamed members of the Rutgers team by falsely calling them prostitutes, Corzine wouldn't have an action against Imus for defamation. Imus didn't call Corzine a "nappy-headed ho," after all. Just as Cardozo wrote in the Palsgraf case that there is no "negligence in the air," so too there is no defamation in the air.
As I said, all of this should be perfectly obvious to anyone who has taken a torts class in the last 80 years. But I think this case (or a hypothetical example with the same structure) could be used to make the notion of proximate cause clearer to students than the way it is typically taught. The post-Legal Realist approach to proximate cause tends to deconstruct it: "a legal conclusion" is how torts teachers sometimes describe the notion of proximate cause. That's not wrong but it's not especially helpful. A better way to explain the concept might be to link it to the law's general antipathy to third-party standing. For the plaintiff to prevail in a suit, it's not enough that the plaintiff suffered an injury as a result of defendant's wrong: what made the defendant's conduct wrongful must be that it violated the plaintiff's rights or interests (unless there is some special reason to permit third-party claims). The Legal Realist point is still valid: To say what duties are owed by whom to what persons or entities requires a legal conclusion; it can't be deduced from first principles. But if phrased in the language of third-party standing, I suspect that much of the mystery surrounding proximate cause would dissolve.
Caveat: I spent about 2 minutes on Westlaw looking to see whether anyone has previously linked the concepts of proximate cause and third-party standing in this way, and couldn't find anything definitive. That doesn't mean there isn't a full scholarly elaboration of the point out there somewhere. There very well might be. But in case there isn't, I hereby declare "dibs" on this topic. (And everyone knows the legal effect of such a declaration!)