I respectfully dissent.
The majority opinion carefully and fairly sets forth the problem. In doing so appellant is criticized for not making an adequate offer of proof and the trial court is criticized because a number of improper reasons were given for rejecting the expert testimony. My conclusion depends upon a different emphasis. The majority requires more in expert qualifications and an offer of proof than I think necessary under these circumstances. I applaud the idea that counsel must fully and properly inform the court of the qualifications of the expert and the proposed testimony to be heard by the jurors. This is important not only for the trial judge, but also to let the appellate court intelligently review the claimed erroneous ruling and its effect on the trial.
*1076In this case the trial court gave considerable time to the question of admitting the proposed testimony, both on and off the record. However, the court was acting in the pr e-McDonald era when judges were more apt than now to guard juries from disguised advice how ultimate issues should be decided. What once was mere “invasion of the jurors’ province” may now be entirely proper even though the jurors may have considerable information on the subject. That eyewitness identification is weak has been a commonplace thought, but may need some expert reinforcement if criminal responsibility depends upon it. That police conduct in a dangerous arrest situation may not be entirely rational, calm and deliberate, and that police officers may have human weaknesses, such as uncertain perceptions and recollections of exciting events, may also be of common knowledge and crucial to a defense in a civil case. The majority opinion does not quarrel with this.
In this case the jurors would decide whether police officers conducted themselves reasonably in a situation few, if any, of the jurors had ever experienced. Not only was the standard of reasonable police conduct at issue, but it depended upon testimony of those who were present and took part in or observed the events. Because of statements made at the time, and later, it was important that the jurors not only judge credibility in its abstract sense, but with a sense of how the circumstances affected the “powers of observation and recollection” of those involved. (People v. McDonald (1984) 37 Cal.3d 351, 371 [208 Cal.Rptr. 236, 690 P.2d 709].)
The ultimate fact of reasonable or unreasonable conduct is a proper subject of expert opinion. An attorney may testify that an insurer acted with bad faith. (Neal v. Farmers Ins. Exchange (1978) 21 Cal.3d 910, 924 [148 Cal.Rptr. 389, 582 P.2d 980].) A state employee who habitually read theft reports and conducted interviews and otherwise investigated illegal sales of water meters, could testify as an expert that the defendants “did not exercise due diligence in purchasing the water meters.” (People v. Cramblit (1978) 84 Cal.App.3d 437, 446 [148 Cal.Rptr. 440].)
The McDonald case may not be a remarkable change in the law. “There are sound and persuasive reasons supporting this trend toward permitting admissibility more readily, rather than rigidly compelling rejection of expert testimony. It is obvious that an overly strict standard of qualification would make it difficult and in some instances virtually impossible to secure a qualified expert witness.” (Brown v. Colm (1974) 11 Cal.3d 639, 646 [141 Cal.Rptr. 128, 522 P.2d 688].) In the Brown case it was recognized that occupational experience and practical knowledge are high on the order of grounds for qualification (our circumstances), but education or observation may be sufficient absent such experience. (Id., at p. 643.) Also, of significance to our case, the court noted the usual deference to the trial court’s *1077exercise of discretion, but added: “Indeed, the exclusion of the sole expert relied upon by a party because of an erroneous view of his qualifications is, in a case where expert testimony is essential, an abuse of discretion as a matter of law requiring reversal.” (Id., at p. 647.) Of course, what is “essential” is a matter of degree. In this case, as in most cases involving professional conduct, expert opinions are deemed of great importance to both the plaintiffs and defense bar.
It is entirely proper for the trial court to try to simplify the case presentation. However, “[e]vidence that is relevant to the prime theory of the defense cannot be excluded in wholesale fashion merely because the trial would be simpler without it.” (People v. McDonald, supra, 37 Cal.3d 351, 372.)
The trial court too much emphasized the “testimony on the ultimate issue” problem, letting it improperly influence his view of whether the expert was qualified. The court’s concern was expressed in this fashion: “[M]y primary thinking was that this is a crucial area for the jury, and that I didn’t feel that this person’s testimony at this time, with his experience, should be given to the jury.”
If a doctor in charge of a hospital review board had been offered in a medical malpractice case to testify concerning typical conditions in the emergency room, or of what happens throughout the hospital when “Code Blue” is sounded, qualifications would be a routine matter. “Although the trial court’s function is to determine the expert’s qualifications, the degree of his knowledge and the weight his testimony will carry are matters for the trier of fact and do not affect the admissibility of his evidence.” (People v. Cramblit, supra, 84 Cal.App.3d 437, 447.) In this case, assuming the subject matter was proper, the qualifications were ample.
The only real question concerns the offer of proof. It was a mixed one, partly in writing and, on several occasions, oral. When shorn of all the problems of letting the jury even hear such testimony, it appears counsel and the court knew what was proposed. Plaintiffs’ counsel was prepared to meet the testimony if admitted, and perhaps looked forward to a defense expert trying to humanize police officers, thus implying a somewhat lower standard of care than popularly supposed.
The sufficiency of the offer is best illustrated by reference to the court’s restatement of the off-record discussions and what it thought would be the testimony and its reasons for not permitting the witness to testify. The trial court fully understood what would be the subject matter, in ultimate fact terminology. We appear to understand the nature of the testimony.
*1078The court refused the offer because the witness would be “telling the jury . . . ‘you should vote this way or that way.’ ” To the contrary, the offer of proof was that the witness would describe typical stress reactions of police officers whose conduct might otherwise be thought by jurors to be more deliberate, correct and credible. In the trial court’s impression, this was crucial, but not a proper subject of expert testimony. The court thought the involved officers and witnesses could provide a full picture of the events, biased as some of them may seem. Though a police expert witness may also appear biased, that was a risk which appellants were willing to suffer, as would a doctor expert testifying in a medical malpractice case. It is not a reason to preclude the testimony if otherwise proper.
I do not criticize the trial judge’s desire to protect the jurors from improper influences. However, “[wjhere an entire class of evidence has been declared inadmissible or the trial court has clearly intimated it will receive no evidence of a particular class or upon a particular issue, an offer of proof is not a prerequisite to raising the question on appeal, and an offer, if made, may be broad and general.” (Beneficial etc. Ins. Co. v. Kurt Hitke & Co. (1956) 46 Cal.2d 517, 522 [297 P.2d 428].)
The majority notes the trial court’s misunderstanding of the applicable rules, and then turns to the insufficiency of the offer of proof as the reason the judgment should be affirmed. In my view, in fairness to appellants’ trial counsel, considerable time was spent elaborating on both qualifications and proposed testimony, only to meet resistance to any effort to “plow new ground.” Counsel then reasonably accepted the court’s ruling when it appeared nothing further could be done but produce the witness. I do not believe the law required the witness to be produced for the taking of his proposed testimony. I agree with the majority that this would have been a prudent course to take. However, counsel was not compelled to produce the witness under the circumstances; in all its patience the trial court did not even hint that personal testimony could make a difference.
I would find the court’s ruling to be “crucial” to the case, using the trial court’s own word. Therefore, the judgment should be reversed.