I dissent from the portion of the opinion which concludes that the trial court did not err in failing to give a cautionary instruction.
Before December, 1975, Rule 30(b)(2), Alaska R.Crim.P., required the court, whether or not requested to do so, to give an instruction on all proper occasions that the oral admissions of a party ought to be viewed with caution. The mandatory nature of this instruction was eliminated by the amended Criminal Rule 30(b), which now reads:
(b) Instructions to Be Given. The court shall instruct the jury on all matters of law which it considers necessary for the jury’s information in giving their verdict.
The mandatory nature of the instruction was eliminated after our decision in Anthony v. State, 521 P.2d 486 (Alaska 1974), in which we reluctantly reversed a conviction due to failure to give the instruction, even though the omission was not called to the attention of the trial court. The obvious reason for the change in the rule was not a belief that the three previously mandated instructions were not important, but to prevent defendants from possibly seeking to take advantage of a court’s oversight whereby the defendant could hope for a not-guilty verdict and be assured that error was present if the jury returned a guilty verdict. That the change cannot be considered an indication that the instructions were of little importance is emphasized by the fact that one of the three instructions previously mandated referred to the basic concept that guilt be established beyond a reasonable doubt. (Former Alaska R.Crim.P. 30(b)(3).)
The trial court in this case did not give a cautionary instruction concerning defendant's out-of-court admissions.
The defendant proposed the following cautionary instruction to the judge:
You should view with caution any oral admissions testified to as having been made by the defendant outside this courtroom. [Emphasis added.]
The judge, when asked why no cautionary instruction concerning the defendant’s out-of-court admissions was being given, said that the proposed instruction referred to statements. Defense counsel correctly noted that the instruction referred to admissions, but the trial judge concluded:
*484Since the defendant had offered himself as a witness his credibility is placed exactly the same as the credibility of any other witnesses who testified here. If, in fact, he had made an admission or a confession or anything close to that the cautionary instruction would have been included.
I agree with the majority that the state’s argument that we must proceed under a plain error analysis is meritless. It is apparent that the issue of the lack of an instruction was adequately brought to the trial court’s attention. The trial judge rejected the proposed cautionary instruction for two reasons: defendant’s statements were not admissions, and the defendant had testified in the case. I believe that the court was in error as to both reasons.
The defendant denied raping A. F. and said he had been at the circus the evening the rape occurred. The state introduced three witnesses who testified, in part, about what the defendant allegedly said. Kim Issermoyer, another girl under age 16, testified that the defendant had asked her to have sex. Dale Cummings testified that the defendant told him to say he only borrowed Cummings’ car in the morning; and Officer Clemens testified that the defendant told him he went to the circus another day but had gone to a company meeting the evening of the rape. As the majority recognizes, all of these statements constituted admissions.
In Stork v. State, 559 P.2d 99 (Alaska 1977), decided under the old version of Rule 30(b), we reversed a manslaughter conviction because the trial judge failed to give the admissions cautionary instruction. In Stork three witnesses testified at trial, describing three different exculpatory versions that the defendant had related to them concerning his wife’s death. We held that these different exculpatory versions of events were admissions.
Stork testified at trial as to his version of his wife’s death. We did not indicate that Stork’s testifying made it unnecessary to give the cautionary instruction.
In the absence of the defendant admitting on the witness stand that he made the statement in question, the fact of his testifying does not lessen the need for the instruction. The admissions cautionary instruction directs the jury to be cautious about what other people say that the defendant said. The cautionary instruction warns the jury about the unreliability of testimony that relates what someone else said. See People v. Bemis, 33 Cal.2d 395, 202 P.2d 82, 84 (1949), quoted in the majority opinion, for an apt expression of the reasons for giving the instruction. Thus, the fact that Kim Issermoyer, Dale Cummings and Officer Clemens testified about what the defendant said calls the instruction into play, irrespective of whether the defendant also testified.1
The principal reason advanced by the trial court for the failure to give the requested instruction was the judge’s mistaken belief that the statements did not constitute admissions:
If, in fact, he had made an admission or a confession or anything close to that the cautionary instruction would have been included.
The majority recognizes that the trial court erred in concluding that the statements did not constitute admissions. Thus, both of the reasons advanced by the trial court for not giving the instruction were erroneous.
The majority says that it is for the trial court to consider the appropriateness of a proper cautionary instruction in light of the state of the evidence and other instructions to be given, and that it was not error to refuse to give the proposed instruction here. Apparently an abuse of discretion standard is being applied. From this I gather that the majority would not consider it to have *485been error for the trial court to have exercised its discretion in favor of giving the instruction. Yet the trial judge clearly indicated that he would have given the instruction if out-of-court admissions had been made. Since the majority recognizes that such admissions were made and the trial court indicated it would have given the instruction had he correctly construed the statements as admissions, it is clear that error was made in failing to give the instruction.
Where a trial court exercises its discretion under a mistake as to applicable law and has indicated that its decision would have been otherwise had it not been laboring under such a mistaken impression, it is self-evident that its discretion was not properly exercised.2 In a similar situation we have remanded a case for resentencing where a court may have imposed a more severe sentence because of a mistaken belief that a statute required a mandatory minimum sentence. Thus, in Call v. State, 511 P.2d 135 (Alaska 1973), where the court imposed a four-year sentence under the mistaken belief that a two-year sentence was mandated, we remanded for resentenc-ing. Although a probation officer had recommended a suspended sentence, the trial court had not indicated that it would have imposed a lesser sentence. Because the court’s discretion may have been based in part on a weighing of the alternatives available under its erroneous view of the applicable law, we remanded. This is obviously a stronger case than Call because we know that the court here would have exercised its discretion to give the instruction were it not for its mistaken view that the statements did not constitute admissions. It follows that there was an abuse of discretion.
Not only do I believe that the abuse of discretion is self-evident, but in my opinion, regardless of the trial court’s error as to applicable law, it would have been an abuse of discretion not to have given the requested instruction. Here the case was dependent on whether the' jury was to believe Alexander or A.F. The oral admissions were of key importance in reaching that decision. No confusion or prejudice would be injected into the case by giving the instruction. If the instruction is ever to be considered applicable, it should be so considered in this case, and the failure to give it when requested, in my opinion, constituted reversible error.
The state argues that the failure to give the instruction, if error, was harmless.3 In Love v. State, 457 P.2d 622, 630 (Alaska 1969), we elaborated upon Alaska’s standard for harmless error on questions that do not implicate rights guaranteed under the federal constitution:
The test is not whether, with the erroneous matter elided from the record, there would be enough evidence to support a conviction. It is not for us to speculate on the outcome at a retrial, absent the erroneous matter. The pivotal question is what the error might have meant to the jury. Our function is to consider not how the error would have affected us if we had tried the case, but how it may have affected a jury of reasonable laymen. It is the impact on their minds which is critical in determining whether an error impaired or affected the substantial interest of the defendant in having a fair trial.
The importance of the evidence and the effect of other instructions are usually the *486two factors that determine the probable impact of the error upon the jury.4 The testimony by the three witnesses about what Alexander said was obviously important to the state’s case. The relevancy of Kim Issermoyer’s testimony was to prove by Alexander’s alleged statement that he had made an overt attempt to have sex with another girl under 16 years of age. This would certainly have some affect on the jury’s deliberations. The alleged attempt to have Dale Cummings give false testimony as to the time his car was used would likely be regarded by the jury as a substantial indication of guilt. The alleged statement to Officer Clemens as to when Alexander went to the circus undermined his entire alibi defense. The importance of this evidence is equivalent to the importance of evidence in other cases where we have found prejudicial error from a failure to give the admissions cautionary instruction.5
The majority argues that other instructions took the place of the cautionary instruction, relying in part on Instruction No. 11, a customary instruction telling the jury to subject the defendant’s testimony to the same tests as other witnesses. Defendant’s argument, however, is that the jury was never told to evaluate the other witnesses' statements about the defendant’s admissions with care. Instruction 11 does not convey the same concept as the oral admissions cautionary instruction. Nor did any of the other instructions contain this key to evaluating the testimony which, until recently, we considered so vital as to mandate a cautionary instruction even in the absence of a request.
Instruction No. 22, another common instruction, told the jury to “decide what testimony is to be believed in the same way you would decide whether to believe something told you out of court.” Instruction 22 is relevant only if we assume that a juror would, from common experience, judge testimony about what other people said with caution.
To indulge this assumption would make the admissions instruction almost always *487superfluous because Instruction 22, or something close to it, is almost always given. The California courts have rejected the rationale that juries will naturally apply the policy behind the cautionary instruction. People v. Bemis, 33 Cal.2d 395, 202 P.2d 82, 84-85 (1949). Most jury instructions embody common sense ideas, but we believe that the judge should remind the jury to apply these ideas. What we said about the accomplice cautionary instruction in Anthony v. State, 521 P.2d 486, 491 (Alaska 1974), is equally applicable here:
The giving of the instruction to view the testimony of an accomplice with distrust clothes the issue with the cloak of the judge’s impartial authority and thus mandates application of that criterion in the jury’s deliberation. For this reason alone, the failure to give the accomplice instruction cannot be regarded as harmless under the circumstances of this case.
I would hold that the failure to give the requested instruction was reversible error mandating a new trial.
. I do agree, however, that the defendant’s testimony concerning his request to Dale Cummings to say he only borrowed Cummings’ car in the morning makes it less necessary to give the cautionary instruction as to that admission. In the absence of a defendant admitting making the out-of-court statement, the cautionary instruction becomes just as important when the jury is confronted with balancing the defendant’s testimony against the alleged out-of-court admission as when the defendant does not take the stand.
. In Lipsett v. United States, 359 F.2d 956, 959 (2d Cir. 1966), the court stated: “[A]n exercise of discretion based on a misconception of the law is an abuse of discretion.” See also American Bd. Cas., Inc. v. Walter Reade-Sterling, Inc., 43 Cal.App.3d 401, 117 Cal.Rptr. 617, 621 (1974); In re Adoption of Driscoll, 269 Cal.App.2d 735, 75 Cal.Rptr. 382, 384 (1969); Pitts v. White, 10 Terry 78, 109 A.2d 786, 788 (Del.1954); Peterson, Howell & Heather v. O’Neill, 314 So.2d 808, 810 (Fla.App. 1975); Sokol v. Liebstein, 9 N.J. 93, 87 A.2d 1, 4 (1952); Associates Discount Corp. v. Wise, 156 Pa.Super. 659, 41 A.2d 418, 419 (1945); First Wis. Nat’l Bk. v. KSW Invest., Inc., 71 Wis.2d 359, 238 N.W.2d 123, 126 (1976).
. See Rule 47(a), Alaska R.Crim.P., which provides:
Harmless Error. Any error, defect, irregularity or variance which does not affect substantial rights shall be disregarded.
. See Stork v. State, 559 P.2d 99, 102 (Alaska 1977) (importance of the evidence); Kristich v. State, 550 P.2d 796, 800-01 (Alaska 1976) (same); Bakken v. State, 489 P.2d 120, 125 (Alaska 1971) (same); cf. Middleton v. State, 577 P.2d 1050, 1054 (Alaska 1978) (curative impact of other instructions where court failed to give cautionary instruction regarding accomplice testimony).
. See Stork v. State, 559 P.2d 99, 103 (Alaska 1977) (testimony of three witnesses about defendant’s differing versions of shooting “substantial factor” in conviction); Bakken v. State, 489 P.2d 120 (Alaska 1971). The facts in Bakken, a statutory rape case, are similar to the facts in this case. The principal evidence against the defendant was the complaining witness’s somewhat inconsistent testimony and testimony by a friend of the defendant that the defendant had commented on the size of the victim’s vagina. The court concluded:
Due to the questionable quality of [the complaining witness’s] testimony, [the friend’s] evidence assumed a crucial role in the conviction of Bakken.
[[Image here]]
Given the closeness of the case and the importance of [the friend’s] testimony concerning Bakken’s purported admission, we believe that the trial court’s failure to give this mandatory cautionary instruction was so obviously prejudicial that we choose to notice the point despite the absence of any objection
Id. at 123, 125 (footnotes omitted).
Contrast Bakken with Kristich v. State, 550 P.2d 796, 800-01 (Alaska 1976), where the failure to give the admissions cautionary instruction in a gambling prosecution was held not prejudicial. The defendant’s statements that the roll, or house money, was across the street was not critical since other “ample evidence” established gambling was occurring on the premises.
Prior to its amendment, Rule 30(b)(2), Alaska R.Crim.P., directed that the court, on all proper occasions, give a cautionary instruction regarding accomplice testimony. In cases dealing with this related area, our analysis of whether prejudice resulted from failure to give a cautionary instruction suggests that the defendant was prejudiced in this case. Compare Anthony v. State, 521 P.2d 486, 489-92 (testimony of accomplice who was only witness placing defendant at scene of crime held a “substantial factor” in conviction) with Middleton v. State, 577 P.2d 1050, 1053-55 (Alaska 1978) (testimony of accomplice about defendant’s participation in robbery not critical in light of eyewitness testimony to the robbery and possession of floor plans).