The Journal of The DuPage County Bar Association

Back Issues > Vol. 13 (2000-01)

A Defense Perspective: Expert Cross-Examination and the Sole Proximate Cause Defense
By Alan J. Brinkmeier

Recent changes in the concepts of expert disclosure (Ill. Sup. Ct Rule 213), and the renewed vigor in the sole proximate cause defense based on a recent Illinois Supreme Court ruling, have suggested a new approach concerning cross-examination of an adverse expert at trial. A defendant asserting the "sole proximate cause" defense seeks to establish that somebody or something other than the defendant’s conduct was the sole cause of the plaintiff’s injuries. This is a causation doctrine, not a liability doctrine. The goal is not to establish that somebody or something else is culpable, but only that defendant’s own conduct, whether culpable or not, did not cause the plaintiff’s injuries. This is the most recent pronouncement from our highest court. See McDonnell v. McPartlin, 192 Ill.2d, 505, 523, 736 N.E.2d 1074, 1085, 249 Ill. Dec. 636, 647 (2000). See also, Simmons v. Garces, 2001 Ill. App. LEXIS 57 (February 7, 2001) – (a defendant is always free to offer evidence that its conduct, negligent or not, was not a proximate cause of the injury).

It has long been the rule that at trial, a defendant has the right to attempt to establish competent evidence that the conduct of a third person, or some other causative factor, is the sole proximate cause of the plaintiff’s injuries. See, Leonardi v. Loyola Univ. of Chicago, 168 Ill.2d 83, 101, 658 N.E.2d 450, 459, 212 Ill Dec. 968, 977 (1995); see also IPI Civil 3d No. 12.04 (conduct of third party as sole proximate cause of plaintiff’s injuries) and IPI Civil 3d No. 12.05 (intervention of "outside agency" – something other than the conduct of defendant – as sole proximate cause).

Under the newly emerging standard in Illinois, the sole proximate cause of a plaintiff’s injury need not be negligent conduct before a defendant is entitled to the instruction. In other words, the defendant need only come forward with sufficient evidence supporting an alternate, sole proximate cause, not evidence of both alternate proximate cause and alternate negligence.

[N]egligent conduct and proximate cause are distinct, albeit related, concepts. Given their relationship, there is a pronounced tendency when considering one to include the other. We cannot, however, ignore the truism that every injury need not proceed from a negligent cause. Accordingly, where there is some competent evidence that the sole proximate cause of a plaintiff’s claimed injury lies in the conduct of someone other than the defendant, the defendant is entitled to have the jury instructed pursuant to the second paragraph of IPI Civil 2d No. 12.04, notwithstanding the absence of evidence tending to establish that the third person’s conduct was negligent. McDonnell, 192 Ill.2d at 523, 736 N.E.2d at 1085, 249 Ill. Dec. at 647 (emphasis added).

The Illinois Supreme Court bolstered its holding in McDonnell that IPI Civil 3d No. 12.04 did not require proof of a third party’s negligence by examining the counterpart instruction, IPI Civil 3d No. 12.05, which directs a jury to consider whether "something" other than the defendant’s conduct was the sole proximate cause of the plaintiff’s injury. The Supreme Court reasoned that "something" justifying the instruction could include "nonnegligent causes". Id. ("IPI Civil 3d No. 12.05 also demonstrates that ‘proximate cause’ is not synonymous with ‘negligent cause.’").

A. Quantum of Proof Necessary for Sole Proximate Cause Instruction

Naturally, a sole proximate cause instruction "requires that there be some evidence to justify the theory of the instruction." McDonnell, 192 Ill.2d at 523, 736 N.E.2d at 1085, 249 Ill. Dec. at 647 (citing Leonardi). Generally speaking, a finding of proximate cause cannot be predicated on surmise or conjecture. Rather, proximate cause must be established with reasonable certainty. Wojtowicz v. Cervantes, 284 Ill.App.3d 524, 532, 672 N.E.2d 357, 362, 219 Ill. Dec. 849, 854 (1st Dist. 1996). "A mere possibility is not sufficient to sustain the burden of proof of proximate cause." Saxton v. Toole, 240 Ill.App.3d 204, 210-11, 608 N.E.2d 233, 238, 181 Ill. Dec 160, 165 (1st Dist. 1992); accord McCullough v. Gallaher & Speak, 254, Ill.App.3d 941, 949, 627 N.E.2d 202, 208, 194 Ill. Dec. 86, 92 (1st Dist. 1993).

The notes on use for the Illinois Pattern Jury Instruction Nos. 12.04 or 12.05 (August 2000) explain that the second paragraph should be used where there is "evidence tending to show" that the sole proximate cause was the conduct of a third person or "something" else. I.P.I. Civil 3d 12.04 Notes on Use.1 "Whether the jury would have been persuaded is not the question. All that is required to justify the giving of an instruction is that there be some evidence in the record to justify the theory of the instruction." Leonardi, 168 Ill.2d at 101, 658 N.E.2d at 449, 212 Ill. Dec. at 977 (emphasis added; quoting Lowe v. Norfolk & W. Ry. Co., 124 Ill.App.3d 80, 118, 463 N.E.2d 792, 79 Ill.Dec. 238 (1984)).

"Circumstantial evidence is sufficient to establish proximate cause if there is a reasonable inference that can be drawn from it." McGraw v. Cegielski, 287 Ill.App.3d 871, 872, 680 N.E.2d 394, 396-97, 233 Ill. Dec. 661, 663-64 (1st Dist. 1996). Circumstantial evidence establishing proximate cause by reasonable inference need not exclude all possible inferences or support only one logical conclusion, so long as the evidence justifies an inference of probability, not mere possibility. Wojtowicz, 284 Ill.App.3d at 532, 672 N.E.2d at 362, 219 Ill., Dec. at 854. Conversely, where the circumstantial evidence supports different reasonable inferences of possible causes, the question of proximate cause is one for the jury. Id., 284 Ill.App.3d at 533, 672 N.E.2d at 362-63, 219 Ill. Dec. at 854-55.

B. The Burdens of Proof and Production for Proximate Cause and Sole Proximate Cause

The plaintiff bears the burden of proof on the issue of proximate cause. Even where a defendant comes forward with evidence supporting a sole proximate cause defense, the burden of proof on proximate cause remains with the plaintiff. Leonardi, 168 Ill.2d at 93-94, 658 N.E.2d at 455, 212 Ill. Dec. at 973. ("Obviously, if there is evidence that negates causation, a defendant should show it. However, in granting the defendant the privilege of going forward, also called the burden of production, the law in no way shifts to the defendant the burden of proof.")

C. Cross Examination of the Plaintiff’s Experts

A witness may be cross-examined about any matters that explain, modify, or discredit his testimony. Tzystuck v. Chicago Transit Auth., 124 Ill.2d 226, 245, 529 N.E.2d 525, 533, 124 Ill. Dec. 544, 552 (Ill. 1988). This rule is equally applicable to the cross-examination of expert witnesses. See Hulman v. Evanston Hosp. Corp., 259 Ill.App.3d 133, 144, 631 N.E.2d 322, 327, 197 Ill. Dec. 319, 330 (1st Dist. 1994). This rule has taken on a greater meaning after the McDonnell v. McPartlin decision.

Indeed, "[t]he principle safeguard against errant expert testimony is cross-examination." Leonardi, 168 Ill.2d at 104, 658 N.E.2d at 460, 212 Ill. Dec. at 978 (quoting Sears v. Rutishauser, 102 Ill.App.2d 402, 407, 466 N.E.2d 210, 212, 80 Ill. Dec. 758, 760 (1984)). While cross-examination is generally limited to matters raised on direct examination, "circumstances resting within the witness’ knowledge may be developed on cross-examination that explain, qualify, discredit or destroy the witness’ direct testimony, even though that material may not have been raised on direct examination." Leonardi, 168 Ill.2d at 105, 658 N.E.2d at 461, 212 Ill. Dec. at 979. Expert testimony elicited on cross-examination, even opinion testimony, need not have been disclosed in advance by the proponent of the witness, nor raised in discovery. Id. (holding standard-of-care expert in medical malpractice action could be cross examined on proximate cause, in order to explain, qualify, discredit or destroy direct testimony).

The thoroughness of an expert’s analysis is fair game on cross-examination. An expert witness can be cross-examined with respect to materials he reviewed but did not rely on, Leonardi, 168 Ill.2d at 105, 658 N.E.2d at 461, 212 Ill. Dec. at 979, materials he failed to utilize or simply disregarded, People v. Pasch, 152 Ill.2d 133, 180, 604 N.E.2d 294, 313, 178 Ill. Dec. 38, 57 (1992), cert. granted, 508 U.S. 959, 113 S.Ct. 2927, 124 L.Ed. 2d 678, cert. dismissed, 510 U.S. 910, 114 S.Ct. 337, 126 L.Ed. 2d 245 (1993), and even the opinions of the cross-examiner’s own experts, id. 152 Ill.2d at 222, 604 N.E.2d at 333, 178 Ill. Dec. at 77 (C. J. Miller, concurring). One caveat is that all such materials must be of a type reasonably relied upon by experts in the witness’ particular field. Id.

In addition, facts, data and opinions supported by the evidence can be varied in questions posed to an expert on cross-examination, in order to elicit a potentially different opinion if the jury were to believe a contrary version of disputed facts. Granberry by Granberry v. Carbondale, 285 Ill.App.3d 54, 59, 672 N.E.2d 1296, 1300, 220 Ill. Dec. 284, 287 (5th Dist. 1996).


There is an emerging trend that the standard to sustain the sole proximate cause defense can be established by effective cross-examination of the plaintiff’s expert witness at trial. The current standard leaves room for nonnegligent causes of the damages or circumstantial evidence that allows reasonable inferences of other causes to support the sole proximate cause defense. 1 The Notes on Use for Instruction No. 12.05 merely refer to the companion Instruction No. 12.04.

1 The Notes on Use for Instruction No. 12.05 merely refer to the companion Instruction No. 12.04.

Alan J. Brinkmeier is a member of the law firm of Merlo, Kanofsky & Brinkmeier, Ltd., a Chicago firm which specializes in complex civil litigation with a concentration in the area of insurance law, including aviation, environmental coverage, product liability, civil rights, municipal liability, medical malpractice, re-insurance and excess insurance coverage questions. Mr. Brinkmeier received his B.A. from Elmhurst College in 1976 and his J.D. from DePaul University College of Law in 1984.

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