Much has been written in the general field of tort law about the cause-in-fact defense as contrasted with the legal concept of proximate cause, but the cause-in-fact defense is underemployed in medical malpractice cases tried in New York courts. The distinction between cause-in-fact, also referred to as “actual cause”, and proximate cause is frequently important enough to present this defense opportunity for the malpractice defendant where situationally appropriate. In most cases, the plaintiff retains the burden of proving through expert testimony that the defendant has departed from the accepted standard of care, and separately that the departure or departures were a proximate cause of the injury complained of, warranting an award of damages to the plaintiff. Reliance upon expert testimony to establish a prima facie case of causal connection is a necessary element of any malpractice claim.

The difference between cause-in-fact and proximate cause is well illustrated by the noteworthy decision of the West Virginia Supreme Court in Jones v. Virginia Railway, 115 W.Va. 663 (1934). In that case, there had been an accident at a railway crossing equipped with lights and a gong to warn those crossing the tracks of oncoming trains. There was also a local ordinance which required that the railway print the word “stop” conspicuously on the roadway, which had not been done prior to the accident. Although there was a failure to mark the pavement as directed by ordinance, the dismissal of the case as a matter of law was upheld. The court reasoned that with operational lights and a gong, there was no factual issue of proximate cause to submit to the jury. As a matter of law, the negligence of the defendant was not the actual cause of the accident. The court held that even if the ordinance had been complied with, the injuries would not have been prevented by markings on the street. Although the jury may well have reached the same conclusion, a valid legal defense is always preferable to reliance on a jury’s determination of factual issues.