Mr. PRESIDING JUSTICE RIZZI
delivered the opinion of the court:
Plaintiff, Rudolfo Sanchez, brought this product liability action against defendant, The Black Brothers Co., to recover damages for injuries sustained to his right hand while attempting to clean a glue spreading machine manufactured by defendant. A jury returned a verdict for defendant. On appeal, plaintiff raises the following issues: (1) whether the trial court improperly admitted evidence of plaintiff’s conduct and whether defense counsel’s closing argument improperly referred to plaintiff’s conduct; (2) whether the trial court erred when it refused plaintiff’s instruction No. 1; and (3) whether the trial court erred when on cross-examination it refused to permit plaintiff to impeach defendant’s expert witness on the basis of a speech he had given to a group of engineers. We reverse and remand for a new trial because of the error involving the cross-examination of defendant’s expert witness.
We first address the issue of the admissibility of evidence relating to plaintiff’s conduct at the time of the accident. Basically, plaintiff contends that because plaintiff’s negligence is not an issue in a product liability case, evidence of plaintiff’s conduct in using the machine at the time of the occurrence should not have been admitted. Plaintiff also argues that a set of 11 point-cleaning instructions should not have been admitted for the same reason. We disagree. The liability issue in a product liability case cannot be tried in a vacuum in which the product is isolated. Rather, the jury should be fully informed as to how the incident occurred and how the plaintiff was using the product at the time of the occurrence.
Moreover, since a trial is an adversary proceeding, both plaintiffs and defendants have a right to introduce evidence to prove their respective theories of the case. Here, defendant’s theory of defense was that the machine was not unreasonably dangerous and that the sole proximate cause of plaintiff’s injury was the conduct of plaintiff’s employer in failing to properly instruct plaintiff regarding the proper procedure for cleaning the machine. If this theory is established by the evidence, the defendant would not be liable. Stanfield v. Medalist Industries, Inc. (1975), 34 Ill. App. 3d 635, 641, 340 N.E.2d 276, 281; Rivera v. Rockford Machine & Tool Co. (1971), 1 Ill. App. 3d 641, 646, 274 N.E.2d 828, 831; Santiago v. Package Machinery Co. (1970), 123 Ill. App. 2d 305, 312, 260 N.E.2d 89, 93.
The evidence to establish this defense theory would necessarily consist of the cleaning instructions supplied and published by defendant, the conduct of the employer in instructing plaintiff, and the manner in which plaintiff was operating or cleaning the machine at the time of the occurrence. It follows that this evidence was admissible even though plaintiff’s negligence was not an issue in the case. (Stanfield, 34 Ill. App. 3d 635, 641, 340 N.E.2d 276, 281.) On this basis, we do not find error in the admission of the evidence.
The fact that there was no error in the admission of evidence which might tend to establish defendant’s theory of defense is important in evaluating the propriety of defense counsel’s closing argument. Defense counsel told the jury:
“MR. TOBIN: These instructions appear on the side of the machine in question.
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And if you recall, Mr. Wood testified to every one of the 11 instructions that were involved concerning the machine and that the first one is to have your hand on the bar at all times.
« « tf
And Mr. Wood testified that when you clean the machine, you have your hand on the bar.
O « «
And that when you have that and you have the hose in the other hand, you have control.
If something happens and you start it, it goes forward, and it stops and reverse, so when you are cleaning it and you follow the method that was designed, the machine is not unreasonably dangerous, because if a man does slip, he has hold of this bar that extends the entire length of the machine.
O « *
And it doesn’t make any difference what level it’s at, whether it’s at the level that Mr. Sanchez had it at [his place of employment] or whether it’s at the level which it’s shipped.
If he has his hand on that and he slips, he is not going to get himself entangled in that machine one way or another.”
Since defense counsel’s remarks were directed to evidence which was properly admitted and to reasonable inferences to be drawn from that evidence to establish defendant’s theory of defense, we find no fault in these remarks. (See Saputo v. Fatla (1975), 25 Ill. App. 3d 775, 788, 324 N.E.2d 34, 44; Maguire v. Waukegan Park District (1972), 4 Ill. App. 3d 800, 805, 282 N.E.2d 6, 9.) There was no allusion in the argument to plaintiff’s negligence barring his recovery. Rather, the argument plainly relates to the issue of proximate cause and the issue of whether the machine was unreasonably dangerous. When viewed in that context, it is a proper argument.
We next address the judge’s refusal to give plaintiff’s instruction No. 1. The instruction states:
“If you decide that the plaintiff has proved all the propositions of this case, then it is not a defense that the plaintiff may have done anything which may have contributed to cause his injury.”
This instruction has the effect of a negative instruction, that is, it tells the jury not to do something with respect to a particular element of the evidence. Generally, negative instructions are to be avoided. Also, plaintiff’s Instruction No. 1 singles out for comment by the court a particular item of the evidence which is not a triable issue in the case. This is improper even though the instruction may be a correct statement of the law. Cf. Eleopoulos v. Dzakovich (1981), 94 Ill. App. 3d 595, 601, 418 N.E.2d 980, 985-86 (where the court held that an IPI instruction which was a correct statement of the law should not have been given because it did not involve a triable issue in the case).
These conclusions are in accord with the policy of the Illinois Supreme Court Committee on Jury Instructions. In the Forward to Illinois Pattern Instructions, Civil (2d ed. 1971) (hereinafter IPI) it is stated at pages VI-VII:
“The criteria underlying the Committee’s policies bears restatement:
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Mr. PRESIDING JUSTICE RIZZI
delivered the opinion of the court:
Plaintiff, Rudolfo Sanchez, brought this product liability action against defendant, The Black Brothers Co., to recover damages for injuries sustained to his right hand while attempting to clean a glue spreading machine manufactured by defendant. A jury returned a verdict for defendant. On appeal, plaintiff raises the following issues: (1) whether the trial court improperly admitted evidence of plaintiff’s conduct and whether defense counsel’s closing argument improperly referred to plaintiff’s conduct; (2) whether the trial court erred when it refused plaintiff’s instruction No. 1; and (3) whether the trial court erred when on cross-examination it refused to permit plaintiff to impeach defendant’s expert witness on the basis of a speech he had given to a group of engineers. We reverse and remand for a new trial because of the error involving the cross-examination of defendant’s expert witness.
We first address the issue of the admissibility of evidence relating to plaintiff’s conduct at the time of the accident. Basically, plaintiff contends that because plaintiff’s negligence is not an issue in a product liability case, evidence of plaintiff’s conduct in using the machine at the time of the occurrence should not have been admitted. Plaintiff also argues that a set of 11 point-cleaning instructions should not have been admitted for the same reason. We disagree. The liability issue in a product liability case cannot be tried in a vacuum in which the product is isolated. Rather, the jury should be fully informed as to how the incident occurred and how the plaintiff was using the product at the time of the occurrence.
Moreover, since a trial is an adversary proceeding, both plaintiffs and defendants have a right to introduce evidence to prove their respective theories of the case. Here, defendant’s theory of defense was that the machine was not unreasonably dangerous and that the sole proximate cause of plaintiff’s injury was the conduct of plaintiff’s employer in failing to properly instruct plaintiff regarding the proper procedure for cleaning the machine. If this theory is established by the evidence, the defendant would not be liable. Stanfield v. Medalist Industries, Inc. (1975), 34 Ill. App. 3d 635, 641, 340 N.E.2d 276, 281; Rivera v. Rockford Machine & Tool Co. (1971), 1 Ill. App. 3d 641, 646, 274 N.E.2d 828, 831; Santiago v. Package Machinery Co. (1970), 123 Ill. App. 2d 305, 312, 260 N.E.2d 89, 93.
The evidence to establish this defense theory would necessarily consist of the cleaning instructions supplied and published by defendant, the conduct of the employer in instructing plaintiff, and the manner in which plaintiff was operating or cleaning the machine at the time of the occurrence. It follows that this evidence was admissible even though plaintiff’s negligence was not an issue in the case. (Stanfield, 34 Ill. App. 3d 635, 641, 340 N.E.2d 276, 281.) On this basis, we do not find error in the admission of the evidence.
The fact that there was no error in the admission of evidence which might tend to establish defendant’s theory of defense is important in evaluating the propriety of defense counsel’s closing argument. Defense counsel told the jury:
“MR. TOBIN: These instructions appear on the side of the machine in question.
« « «
And if you recall, Mr. Wood testified to every one of the 11 instructions that were involved concerning the machine and that the first one is to have your hand on the bar at all times.
« « tf
And Mr. Wood testified that when you clean the machine, you have your hand on the bar.
O « «
And that when you have that and you have the hose in the other hand, you have control.
If something happens and you start it, it goes forward, and it stops and reverse, so when you are cleaning it and you follow the method that was designed, the machine is not unreasonably dangerous, because if a man does slip, he has hold of this bar that extends the entire length of the machine.
O « *
And it doesn’t make any difference what level it’s at, whether it’s at the level that Mr. Sanchez had it at [his place of employment] or whether it’s at the level which it’s shipped.
If he has his hand on that and he slips, he is not going to get himself entangled in that machine one way or another.”
Since defense counsel’s remarks were directed to evidence which was properly admitted and to reasonable inferences to be drawn from that evidence to establish defendant’s theory of defense, we find no fault in these remarks. (See Saputo v. Fatla (1975), 25 Ill. App. 3d 775, 788, 324 N.E.2d 34, 44; Maguire v. Waukegan Park District (1972), 4 Ill. App. 3d 800, 805, 282 N.E.2d 6, 9.) There was no allusion in the argument to plaintiff’s negligence barring his recovery. Rather, the argument plainly relates to the issue of proximate cause and the issue of whether the machine was unreasonably dangerous. When viewed in that context, it is a proper argument.
We next address the judge’s refusal to give plaintiff’s instruction No. 1. The instruction states:
“If you decide that the plaintiff has proved all the propositions of this case, then it is not a defense that the plaintiff may have done anything which may have contributed to cause his injury.”
This instruction has the effect of a negative instruction, that is, it tells the jury not to do something with respect to a particular element of the evidence. Generally, negative instructions are to be avoided. Also, plaintiff’s Instruction No. 1 singles out for comment by the court a particular item of the evidence which is not a triable issue in the case. This is improper even though the instruction may be a correct statement of the law. Cf. Eleopoulos v. Dzakovich (1981), 94 Ill. App. 3d 595, 601, 418 N.E.2d 980, 985-86 (where the court held that an IPI instruction which was a correct statement of the law should not have been given because it did not involve a triable issue in the case).
These conclusions are in accord with the policy of the Illinois Supreme Court Committee on Jury Instructions. In the Forward to Illinois Pattern Instructions, Civil (2d ed. 1971) (hereinafter IPI) it is stated at pages VI-VII:
“The criteria underlying the Committee’s policies bears restatement:
First, the Committee has been opposed to negative instructions, that is, instructions which tell the jury to not do something.
Second, the Committee has not recommended instructions which single out a particular item of evidence for comment, even where there is judicial authority for the instruction.
# tt «
Fourth, and perhaps most important, the Committee has opposed over particularizing. It has preferred to rely upon one instruction which is general in nature and has avoided creating a number of instructions on a subject which is adequately covered by the single general instruction.
Underlying all these considerations has been a major policy. We have viewed the problem of communicating law to the jury as one best handled by a partnership between court and trial counsel rather than by the court alone. The Court will in understandable language fairly state the law, permitting counsel on each side to supply adversary emphasis, rather than try to neutralize partisan instructions, sounding first like plaintiff’s counsel and then in the next sentence like defense counsel. In brief, on many occasions when the Committee has rejected an instruction, it has felt not so much that the point ought not be told to the jury, but rather that it should be told to the jury by counsel rather than by the Court.”
Accordingly, the court should not instruct the jury as to the insignificance of plaintiff’s conduct in a product liability case. Counsel in his closing argument may adequately inform the jury of the insignificance of plaintiff’s conduct with respect to the issues and his theory of the case without the “assistance” of comment by the court on that specific element of the evidence.
The facts in a product liability case are often intermixed and interrelated when applied to the issues. It is important in such cases that the court refrain from commenting on and, in effect, giving judicial emphasis to a certain element of the evidence that is not a triable issue in the case. Otherwise, the jury may place more importance on that element of the evidence than it does on the issues which are being tried. Also, when a court comments on a specific element of the evidence that is not a triable issue in the case, it tends to distract the focus of the jury’s attention from the issues stated in the issues instruction to that particular element of the evidence.
In addition, plaintiff’s instruction No. 1 obviously refers to either the negligence of the plaintiff or misuse. To the extent it relates to the negligence of the plaintiff, it should not be given because it is misleading. Since the negligence of the plaintiff is not a triable issue in a product liability case, it does not appear in either the issues or the burden of proof instruction. (See IPI Civil Nos. 400.01, 400.02.) If a negative instruction dealing with plaintiff’s negligence is given to the jury, it would implicitly engraft the false issue of plaintiff’s negligence onto the issues and burden of proof instructions, and thus, it would be misleading.
To the extent plaintiff’s instruction No. 1 relates to misuse, the Illinois Supreme Court Committee on Jury Instructions recommends that no instruction on misuse be given. We agree with the reasons and conclusions of the Committee. (See IPI Civil No. 400.08.) Moreover, the issue of misuse arises in connection with plaintiff’s proof of an unreasonably dangerous condition, or proximate cause, or both. (Williams v. Brown Manufacturing Co. (1970), 45 Ill. 2d 418, 431, 261 N.E.2d 305, 312; Gallee v. Sears Roebuck & Co. (1978), 58 Ill. App. 3d 501, 503, 374 N.E.2d 831, 834.) Thus, defendant’s denial that the product contained an unreasonably dangerous condition which proximately caused plaintiff’s injury raised the issue of misuse. (IPI Civil Nos. 400.00, 400.08, Comments.) However, by distinguishing “the propositions of this case” from anything “the plaintiff may have done ° * which may have contributed to cause his injury,” plaintiff’s instruction No. 1 would, in effect, tell the jury that misuse is not an element of any proposition in the case and that it will not bar plaintiff’s right to recover. On this point, the specially concurring opinion states, “If plaintiff has proved all the propositions of his case, then misuse is no longer an issue.” The problem with that statement is that it does not take into account the effect of the instruction. By virtue of the instruction, plaintiff’s misuse would never become an element of any proposition of plaintiff’s case for the jury to consider because it is distinguished in the instruction from the propositions of plaintiff’s case.
Further, the above analysis leads to another reason why plaintiff’s instruction No. 1 should not be given in this case. Since the instruction begins “If you decide that the plaintiff has proved all the propositions of this case, then it is not a defense,” the instruction does not effectively tell the jury anything useful. If a plaintiff has proved all the propositions of the case, then the verdict must be in favor of the plaintiff in any case unless an affirmative defense was raised. In the present case, no affirmative defense was raised. Thus, the instruction unduly emphasizes a single element of the evidence without any purposeful instruction to the jury. In this regard, the specially concurring opinion states that the form of plaintiff’s instruction No. 1 is correct because IPI Civil Nos. 400.09 and 400.10 begin with the same wording. However, since they are not involved in this case, we do not address the approval or disapproval of those instructions.
The specially concurring opinion also places emphasis on a comparison of plaintiff’s instruction No. 1 with IPI Civil No. 180.17. We do not find this comparison persuasive. IPI Civil No. 180.17 is a Structural Work Act case instruction. In those cases, the conduct of the plaintiff does not bar the plaintiff’s cause of action. In a product liability case, however, the conduct of the plaintiff may bar his recovery if it amounts to misuse of the product. (Williams, 45 Ill. 2d 418, 431, 261 N.E.2d 305, 312; Gallee, 58 Ill. App. 3d 501, 502, 374 N.E.2d 831, 834; IPI Civil No. 400.00, Comment.) Thus, merely because an instruction relating to plaintiff’s conduct may be proper in a Structural Work Act case does not mean that the instruction or a similar instruction is proper in a product liability case. That the two types of cases are significantly different is exemplified by the fact that they are treated in completely different sections of the IPI.
Lastly, with respect to the comparison of plaintiff’s instruction No. 1 with IPI Civil No. 180.17, it must be noted that the IPI section for Structural Work Act cases (which includes No. 180.17) was included in the bound volume of IPI Civil published in 1971. The IPI instructions for product liability cases were first published in 1977, and significantly, they do not include an instruction similar to IPI Civil No. 180.17. We can only conclude that the Illinois Supreme Court Committee on Jury Instructions considered and rejected incorporating No. 180.17 or a similar instruction in product liability cases.
We do not disagree with the statement in the specially concurring opinion that the “IPI is not the exclusive source of jury instructions” and that there are instances where an instruction not contained in IPI should be given. (See Ill. Rev. Stat. 1979, ch. 110A, par. 239(a).) However, that principle does not detract from the significance of the fact that plaintiff’s instruction No. 1 is not in IPI and that the IPI Committee apparently chose not to include such an instruction in the instructions for product liability cases. Moreover, plaintiff’s instruction No. 1 is neither simple, impartial nor free from argument. (See Logue v. Williams (1969), 111 Ill. App. 2d 327, 336, 250 N.E.2d 159, 164.) As a result, we do not believe the instruction complies with Supreme Court Rules 239(a).
Next, we address the issue involving the cross-examination of defendant’s expert witness. Plaintiff’s counsel informed the judge that he intended to use the expert witness’ speech, set forth in the specially concurring opinion, to demonstrate his interest, bias, motive and prejudice. The judge ruled in limine that the speech could not be used for any purpose during cross-examination. This was reversible error.
Expert testimony on matters not within common knowledge and experience is sometimes necessary to enable jurors to determine the factual issues submitted to them. However, the expert witness is usually a hired partisan. Moreover, it is unlikely that he could be successfully prosecuted for perjury on the basis of his opinion testimony. Thus, while the expert’s opinion has the sanction of an oath, it lacks the substantial safeguard of truth that may be applied to the testimony of other witnesses. For these reasons, counsel must be given the widest possible latitude during cross-examination to demonstrate any interest, bias or motive of the expert witness to testify. Cf. People v. Barr (1972), 51 Ill. 2d 50, 51-52, 280 N.E.2d 708, 710; People v. Garrett (1976), 44 Ill. App. 3d 429, 436-37, 358 N.E.2d 364, 370.
Here, a jury could conclude that the statements made by the expert witness before a group of engineers in a formal setting demonstrate an interest, bias or motive to testify favorably for the party calling him as an expert witness in a product liability case. Thus, rather than allowing plaintiff’s counsel the widest possible latitude on cross-examination to establish the interest, bias or motive of the witness to testify favorably for defendant, the trial court unduly restricted the cross-examination. Since the credibility of the witness was crucial to the defense of the case, the error was prejudicial and necessitates a new trial.
However, the credibility of a witness is for the jury to determine. As a result, we do not reach any conclusion concerning the character of the statements made by the expert witness or the credibility of his testimony. Any such characterization or conclusion may or may not be made by a jury after seeing and hearing the witness testify.
Accordingly, the judgment is reversed, and the case is remanded for a new trial solely because of the error in refusing to allow plaintiff’s counsel to use the expert witness’ speech to impeach him. In a new trial, the instruction designated herein as plaintiffs instruction No. 1 should not be given to the jury.
Reversed and remanded.
McGILLICUDDY, J., concurs.