delivered the opinion of the court.
This is an appeal by plaintiffs from a judgment entered on a jury verdict in favor of the defendants in a consolidated personal injury action involving a mutiplecar accident.
On January 27, 1961, at 8:30 p. m., plaintiff, Homer Sullivan, wаs traveling in a southerly direction on Mannheim Road, a four-lane highway near Fullerton Avenue. Plaintiff, Martin Gariti, was driving his car behind Sullivan’s vehicle. Defendant, Henry L. Olds, was proceeding northbound on Mannheim Road in a vehicle rented from the Hertz Corporation by his employer, the Phelps-Dodge Copper Products Company. The Sullivan and Olds vehicles collided, and the Olds vehicle then struck the Gariti car. Henry L. Olds died of injuries four days after the occurrence. Plaintiffs, Sullivan and Gariti, filed separate suits (which were later consolidated on the motion of the defendants) against Phelps-Dodge Copper Products Company and the administrator of the estate of Olds. After the death of Homer Sullivan, during the pendency of his suit, the administrator of his estate was substituted as a plaintiff.
There was a factual dispute as to which car crossed the center line and whether Olds wаs or was not acting as the agent of his employer. Plaintiffs’ evidence included testimony by plaintiff, Martin Gariti, that he had been following the Sullivan car for four or five blocks and at no time did his car or the Sullivan car leаve the inner southbound lane. Each car was proceeding at about 40 m. p. h. At the time Gariti saw the collision in front of him, the Sullivan car was still in the inner southbound lane, although Gariti was unclear as to what exactly had hаppened. James Bennett, who was working at a gasoline station on Mannheim Road between Fullerton and Grand, heard a crash and observed that there had been a collision between the Sullivan car аnd the car driven by Olds. At that time he saw that the Olds car was still moving in a north by northwest direction with part of the car on each side of the center line and was traveling at a speed of not less than 60 m. p. h., possibly as great as 80 m. p. h. Trooper George Huizenga testified that he was present following the accident when a fellow state police officer asked Mr. Sullivan questions and he answered them. Mrs. Sullivan testified that while hospitalized after the accident her husband was found to have diabetes. Prior to that time he had made no complaint about diabetes and had never seen a doctor for that condition. When he left the hospital, he was given some needles and insulin for the treatment of diabetes.
The sole witness for the defense on the issue of liability for the accident was Dr. George J. Cooper, an expert witness. Dr. Cooper was asked, over objections, a hypothetical question which included the general facts of the occurrence and the condition of diabetes found to exist in the hypothetical man (Sullivan). The doctor answered that he did have an opinion based upon a reasonable medical or surgical certainty whether the accident on the highway might or could have a causal connection with a сondition of diabetes found in the hypothetical person. He said:
I have an opinion. And that is based on the facts that this individual was an unknown, untreated diabetic, and these individuals vary in their ability to respond to situations. This is the higher level of consciousness, and one. does not have to lose consciousness to lose judgment and all of its faculties, coordination, and recall, plus analysis at a split second. When we arе dealing with a diabetic who even though some who are under treatment and not properly managed, not properly controlled, they first show defects in the upper brain processes — memory, recall, analysis, judgment. And a split-second change in these reactions can produce a loss of control for a split moment — of the extremity control — and he can lose control of the vehicle or make a mis judgment.
The same holds true with visual perception, which is also one of the higher levels of the brain, the ability to visualize in depth. This is one of the finer nerve endings of the brain. It’s the one that suffers first from diabetes. And in an unmаnaged case — and there is no such thing as mild diabetes because any diabetic, if he doesn’t get managed properly, can proceed to coma and die just like an individual who is on a heavy dose оf insulin.
And in my opinion this man momentarily had a defect in his thought processes that caused the accident.
On cross-examination, Dr. Cooper testified that the factors that influenced his opinion were Sullivan’s confusion after the accident, his failure to recall what had happened, Sullivan’s being a diabetic sorely in need of treatment and the accident itself. It was also apparent from his answers that Dr. Cooper was familiar with the results of tests made on Sullivan, but not included in the hypothetical question. Dr. Cooper testified that he understood the accident in the question put to him as occurring when the Sullivan car partially swervеd across a lane and hit the Olds car, which then hit the Gariti car. When asked if his opinion would be different if the Sullivan car had not swerved, but had remained in its lane, Dr. Cooper replied that if the hypothetical man didn’t swerve and didn’t lose control no matter how minutely or for how brief a time, a different problem was posed, and his opinion would be somewhat different. While his subsequent explanation is somewhat unclear, it seems that it was his opinion that the facts about diabetes wouldn’t change, but the initiating factor of the collision might be different.
Dr. Elmer Crisp testified on behalf of the plaintiffs in rebuttal, that based on the urinalysis of Sullivan done immediately after thе accident it would have been impossible for his condition to have caused him to lose physical coordination and thereby lose control of his car.
“The opinion of an expert is to be allowed only if it is based on and supported by facts in evidence.” Kanne v. Metropolitan Life Ins. Co., 310 Ill App 524, 530,
Similarly, in Butler v. Palm, 36 Ill App2d 351,
In the case at bar, the medical witness for the defense made several assumptiоns on which he based his opinion. The most important and most unwarranted of these were that Sullivan was a diabetic, and that it was Sullivan whose car swerved across the center line before the collision. There was evidence that Sullivan was given insulin for a diabetic condition after the accident. There was no evidence showing that Sullivan was diabetic before the accident, or if he was, as to the extent of his condition. There was absolutely no evidence in the record on which any expert could properly express an opinion that Sullivan was suffering to such an extent from the possible consequences and effects of an unrecognized and undiagnosed diabetic condition that he could have become uncoordinated and allowed his automobile to go onto the wrong side of the highway at the time of thе accident.
It was clear from the cross-examination of Dr. Cooper that he also assumed that it was Sullivan’s car which swerved across the center line before the collision. There was no evidence to support this assumption, and what evidence there was tended to prove that Sullivan remained in his lane. This was the critical fact in the case. If the defense had proven what the doctor assumed, his tеstimony would have been unnecessary. Since it was not proven, his testimony was highly speculative and improper.
Doctor Cooper testified that in his opinion, “this man had a defect in his thought processes that сaused the accident.” It is not the province of an expert to act as judge or jury. He cannot be called upon to decide a question of fact. He may, however, make assumptions which havе a basis in the evidence, although controverted by other evidence. That is the proposition for which Gus T. Handge & Son v. Industrial Commission, 33 Ill2d 201,
Since there must be another trial, we do not deem it necessary to consider other issues raised by the plaintiffs. For the reasons stated, the judgment of the Circuit Court is reversed, and the cause is remanded for another trial.
Reversed and remanded.
MURPHY and ADESKO, JJ., concur.
