Plaintiff appeals from a jury verdict in favor of all defendants on his medical malpractice cause of action.
Plaintiff was seriously injured in a motorcycle-car crash and taken in critical condition and great pain to the emergency room at the defendant city’s hospital. Defendant Dr. DeWitt, plaintiff’s family physician, met him at the hospital and ordered numerous X-rays. Dr. DeWitt summoned defendant Dr. Mahaney, an orthopedic surgeon, who assumed care of the patient, reviewed the X-rays, and, pursuant thereto, ordered traction of the right leg in treatment of an apparent fracture of the right acetabulum (hip socket).
Unbeknownst to Dr. Mahaney, a hospital techni*124cian had mislabeled an X-ray: plaintiff was actually suffering a fracture of his left hip. This error was discovered on the next day by defendant Dr. Gesink, a radiologist, who corrected the X-ray label and dictated a report for Drs. Mahaney and DeWitt with a copy for plaintiffs file. For some reason, Dr. Mahaney did not become aware of the error until his request for follow-up X-rays 11 days later. Traction remained for this period on the "wrong” leg.
Plaintiffs appeal alleges nine instances of reversible error. The one that causes the most difficulty is the assertion that the trial judge should have directed a verdict for plaintiff, particularly as against the defendant city, owner and operator of the hospital.
It is undisputed that the hospital employee mislabeled the X-ray, and that treatment would have been different otherwise. Despite defendants’ various contentions that such "human” errors are inevitable, it is obvious that mislabeling an X-ray, a blatant breach of a hospital’s duty of care to a patient, is an act of ordinary, "nonmedical” negligence. Accordingly, plaintiffs counsel asked at trial for a directed verdict on the "issue of liability”, while leaving "the issue of damages to the Jurors”.
Unfortunately, such a partial or specialized directed verdict does not comport with a cause of action for medical malpractice, a tort claim in negligence. As stated by the Supreme Court in Morgan v Engles, 372 Mich 514, 516; 127 NW2d 382, 383-384 (1964):
"It is obviously the law that in order to recover for the negligence of a physician, plaintiff must show that such negligence was a proximate cause of the injury for which damages are sought.” (Emphasis added.)
*125The required elements for a cause of action "for damages arising out of tortious injury to a person” are listed in Connelly v Paul Ruddy’s Equipment Repair & Service Co, 388 Mich 146, 150; 200 NW2d 70, 72 (1972):
"(1) The existence of a legal duty by defendant toward plaintiff.
"(2) The breach of such duty.
"(3) A proximate causal relationship between the breach of such duty and an injury to the plaintiff.
"(4) The plaintiff must have suffered damages.”
There is significant expert testimony on the record that could have supported a conclusion by the jury that plaintiffs resultant hip condition was proximately caused by the accident rather than by the treatment. Defendants’ independent expert, Dr. Greene, characterized the results of the treatment as "rather ideal”; the testimony of plaintiffs own expert, Dr. Badgley, indicates that the accident unaggravated by treatment could be the cause of the continuing difficulties. Reasonable men could differ as to the question of proximate cause, and we cannot therefore find liability as a matter of law. See Siirila v Barrios, 58 Mich App 721, 725; 228 NW2d 801 (1975). The trial judge properly denied a directed verdict in favor qf plaintiff.
Plaintiff also contends that the trial judge’s application of GCR 1963, 511.5 denied him equal protection of the law by granting each defendant three peremptory challenges (12 total) as against his total of three. The court rule enables the judge to make a rational classification based on diversity of interests, and the record clearly indicates that the defendants were separate, and potentially antagonistic, parties. Further, as there were no limi*126tations on the number of challenges for cause, plaintiff retained the reasonable opportunity to assure himself of the jury’s impartiality. We do not find error in this issue.
Plaintiff next contends that he should have been allowed to cross-examine defendant Dr. Gesink as. to a cross-complaint filed on his behalf but withdrawn prior to trial. The trial judge determined on the record that Dr. Gesink was without knowledge of this pleading prepared by his attorney, and denied plaintiff’s request to cross-examine on this ground and on the ground of irrelevancy. While pleadings are admissible for impeachment purposes, it is obvious that the pretrial documentary fencing in this case has no relevance to the credibility of Dr. Gesink. Further, cross-examination of Dr. Gesink on this question would run a serious risk of impropriety by being misinterpreted by the jury as substantive evidence of negligence, and, in any case, Dr. Gesink (a radiologist) is admittedly without competence to testify as to any negligence of his codefendant orthopedist or family physician. The trial judge’s ruling in exclusion of this testimony was not erroneous.
Plaintiff also asserts error in the admission into evidence of a release that he negotiated with the driver of the automobile that hit him, and error in the trial judge’s instruction to the jury that the consideration received by plaintiff from the driver for the release should be deducted from the amount of any damages resulting from malpractice. These assertions are answered in the negative by, respectively, Sobotta v Vogel, 37 Mich App 59; 194 NW2d 564 (1971), and Cooper v Christensen, 29 Mich App 181; 185 NW2d 97 (1970).
Plaintiff argues error in the trial judge’s permission of cross-examination as to his "experimental” *127use of marijuana. Defendants counter that plaintiff’s allegation of substantial damages for mental anxiety and psychiatric treatment renders such questioning relevant.
We tend to agree with plaintiff. This is scarcely a case such as People v Talaga, 37 Mich App 100; 194 NW2d 462 (1971), where heroin addiction was adjudged relevant and material on credibility. It is a plain fact that a significant percentage of college age people have "experimented” with marijuana. Further, defendants presented no evidence of a causal connection between use of marijuana and psychological difficulties. This questioning is specifically disapproved.
Nevertheless, we believe that, in the context of this record,, the error was not sufficiently prejudicial so as to require a new trial under GCR 1963, 529.1.
Plaintiff’s remaining allegations of error have been considered and determined to be without merit. The verdict of the jury is affirmed.
M. J. Kelly, J., concurred.