Abrams, J.
Convicted of murder in the second degree, armed assault with intent to murder, and assault and battery by means of a dangerous weapon, the defendant, John F. Kappler, Jr., appeals. The trial focused on the issue of criminal responsibility. After the verdicts, the defendant moved to set aside the verdicts and for required findings of not guilty or, in the alternative, for a new trial. The motions were denied. The defendant alleges error in the denial of his motion for required findings of not guilty, in the allowance of the Commonwealth’s rebuttal testimony, in the jury instructions, and in the denial of his motion for a new trial. We transferred this case from the Appeals Court on our own motion. We affirm.
We summarize the facts in the light most favorable to the Commonwealth. Commonwealth v. Rhoades, 379 Mass. 810, 815 (1980). The defendant, a sixty year old retired anesthesiologist from California, and his wife were visiting their daughter in Medford. On the morning of April 14, 1990, the defendant was to leave Boston and drive to New York City to meet his son. The wife was to fly home to California that day. The defendant awoke at 6 a.m. and spent time packing the car, rearranging things. He had a brief conversation about California with an elderly man who happened to walk by the automobile. The defendant’s daughter’s fiancé arrived. A friend of his daughter drew him a map of the route to New York. The defendant then ate breakfast with his wife, his daughter, her fiancé, and her friend. The defendant said that he had to get going because he wanted to be on his way by 10 a.m. No one noticed anything unusual about the defendant.
The defendant drove through a red light on Alewife Brook Parkway. He was staring straight ahead. He then drove his car onto the footpath adjacent to Alewife Brook Parkway and proceeded to strike two individuals, killing one. The defendant followed the contours of the path, did not sound his horn, did not swerve, and did not stop. After striking the sec- [576]*576and victim, as he drove away he accelerated his automobile and returned to the road. The defendant left his automobile behind a house in a driveway. The automobile was not visible from the street.
According to the defendant, he wandered around the vicin- ■ ity. He also said that he returned to the area of the incident. Further, he called his daughter’s home and left a message saying, “Oh, I thought I might catch you there. Maybe you could pick me up.” He then took a bus to New York City and checked into a hotel. The next day he called his wife and told her he thought he had killed someone. She told him to go to the Payne-Whitney Psychiatric Clinic, a part of New York Hospital. The defendant did so. The defendant’s son met him at the emergency room there, where, according to the defendant’s son, the defendant appeared confused. According to the son, the defendant attacked him and attempted to strangle him.
Prior to trial, the defendant notified the Commonwealth that, at trial, he would claim that he lacked criminal responsibility. The judge ordered the defendant to be evaluated for his competency and his criminal responsibility. Dr. Prudence Baxter, who conducted the evaluation, concluded that the defendant was competent to stand trial, but determined that he was suffering the symptoms of mental illness and therefore recommended further evaluation in order to determine whether he was criminally responsible.
The defendant, through his wife and medical history, presented evidence of his long but sporadic history of mental illness and auditory hallucinations.1 One defense expert, Dr. Martin Kelly, testified that the defendant suffered from atyp[577]*577ical psychosis and, although able to appreciate the wrongfulness of his conduct, was unable to conform his conduct to the requirements of the law. Another expert, Dr. Ronald Ebert, testified that, in his opinion, the defendant was unable either to appreciate the wrongfulness of his conduct or to conform his conduct to the law. He diagnosed the defendant as suffering either from atypical psychosis with paranoid features or schizo-affective disorder.
Two additional experts who testified for the defense did not state opinions as to whether the defendant was criminally responsible. Dr. Robert Aranow testified as an expert in psychiatry. He stated that, in his opinion, the defendant suffered from a mental disease he called atypical psychosis on the date of the incident. Dr. Aranow characterized the defendant’s psychosis as “extremely” unusual. He also acknowledged that the defendant made a number of inconsistent and contradictory statements about the events occurring on the date of the incident. Then Dr. Lloyd Price testified that on the date of the incident, the defendant was suffering from psychosis. He categorized the defendant’s mental disease as atypical psychosis with affective features. Neither Dr. Ara-now nor Dr. Price expressed an opinion whether the defendant was able to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law. See Commonwealth v. McHoul, 352 Mass. 544, 546-547 (1967).
The Commonwealth called three witnesses in rebuttal. None of these witnesses stated a conclusion as to whether the defendant was able to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of law, although each offered testimony that supported the Commonwealth’s position that the defendant was sane as part of the testimony.
1. The motion for required findings of not guilty. The defendant moved for required findings of not guilty, both at the close of the Commonwealth’s case2 and at the close of all the [578]*578evidence. The motions were denied. The defendant appeals, claiming that there was insufficient evidence to support jury verdicts finding him sane beyond a reasonable doubt.
In reviewing the denial of a motion for a required finding, we “must determine whether the Commonwealth’s evidence, ‘considered in its light most favorable to the Commonwealth, was sufficient to permit the jury to infer the existence of [criminal responsibility].’ ” Commonwealth v. Shelley, 381 Mass. 340, 346 (1980). In addition, “the evidence and the inferences permitted to be drawn therefrom must be ‘of sufficient force to bring minds of ordinary intelligence and sagacity to the persuasion of [sanity] beyond a reasonable doubt.’ ” Commonwealth v. Latimore, 378 Mass. 671, 677 (1979), quoting Commonwealth v. Cooper, 264 Mass. 368, 373 (1928).
The defendant stipulated to the fact that he drove the car that struck two victims, killing one of them. In its case in chief, the Commonwealth presented evidence linking the defendant’s car to the injuries and showing that one victim died as a result of injuries received when he was struck by the car. There was no error in denying the motion for a required finding of not guilty at the close of the Commonwealth’s case.
“A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law.” Commonwealth v. McHoul, supra at 546-547. When a defendant claims that he is not criminally responsible for his acts, the Commonwealth bears the burden of proving beyond a reasonable doubt that the defendant is sane.
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Abrams, J.
Convicted of murder in the second degree, armed assault with intent to murder, and assault and battery by means of a dangerous weapon, the defendant, John F. Kappler, Jr., appeals. The trial focused on the issue of criminal responsibility. After the verdicts, the defendant moved to set aside the verdicts and for required findings of not guilty or, in the alternative, for a new trial. The motions were denied. The defendant alleges error in the denial of his motion for required findings of not guilty, in the allowance of the Commonwealth’s rebuttal testimony, in the jury instructions, and in the denial of his motion for a new trial. We transferred this case from the Appeals Court on our own motion. We affirm.
We summarize the facts in the light most favorable to the Commonwealth. Commonwealth v. Rhoades, 379 Mass. 810, 815 (1980). The defendant, a sixty year old retired anesthesiologist from California, and his wife were visiting their daughter in Medford. On the morning of April 14, 1990, the defendant was to leave Boston and drive to New York City to meet his son. The wife was to fly home to California that day. The defendant awoke at 6 a.m. and spent time packing the car, rearranging things. He had a brief conversation about California with an elderly man who happened to walk by the automobile. The defendant’s daughter’s fiancé arrived. A friend of his daughter drew him a map of the route to New York. The defendant then ate breakfast with his wife, his daughter, her fiancé, and her friend. The defendant said that he had to get going because he wanted to be on his way by 10 a.m. No one noticed anything unusual about the defendant.
The defendant drove through a red light on Alewife Brook Parkway. He was staring straight ahead. He then drove his car onto the footpath adjacent to Alewife Brook Parkway and proceeded to strike two individuals, killing one. The defendant followed the contours of the path, did not sound his horn, did not swerve, and did not stop. After striking the sec- [576]*576and victim, as he drove away he accelerated his automobile and returned to the road. The defendant left his automobile behind a house in a driveway. The automobile was not visible from the street.
According to the defendant, he wandered around the vicin- ■ ity. He also said that he returned to the area of the incident. Further, he called his daughter’s home and left a message saying, “Oh, I thought I might catch you there. Maybe you could pick me up.” He then took a bus to New York City and checked into a hotel. The next day he called his wife and told her he thought he had killed someone. She told him to go to the Payne-Whitney Psychiatric Clinic, a part of New York Hospital. The defendant did so. The defendant’s son met him at the emergency room there, where, according to the defendant’s son, the defendant appeared confused. According to the son, the defendant attacked him and attempted to strangle him.
Prior to trial, the defendant notified the Commonwealth that, at trial, he would claim that he lacked criminal responsibility. The judge ordered the defendant to be evaluated for his competency and his criminal responsibility. Dr. Prudence Baxter, who conducted the evaluation, concluded that the defendant was competent to stand trial, but determined that he was suffering the symptoms of mental illness and therefore recommended further evaluation in order to determine whether he was criminally responsible.
The defendant, through his wife and medical history, presented evidence of his long but sporadic history of mental illness and auditory hallucinations.1 One defense expert, Dr. Martin Kelly, testified that the defendant suffered from atyp[577]*577ical psychosis and, although able to appreciate the wrongfulness of his conduct, was unable to conform his conduct to the requirements of the law. Another expert, Dr. Ronald Ebert, testified that, in his opinion, the defendant was unable either to appreciate the wrongfulness of his conduct or to conform his conduct to the law. He diagnosed the defendant as suffering either from atypical psychosis with paranoid features or schizo-affective disorder.
Two additional experts who testified for the defense did not state opinions as to whether the defendant was criminally responsible. Dr. Robert Aranow testified as an expert in psychiatry. He stated that, in his opinion, the defendant suffered from a mental disease he called atypical psychosis on the date of the incident. Dr. Aranow characterized the defendant’s psychosis as “extremely” unusual. He also acknowledged that the defendant made a number of inconsistent and contradictory statements about the events occurring on the date of the incident. Then Dr. Lloyd Price testified that on the date of the incident, the defendant was suffering from psychosis. He categorized the defendant’s mental disease as atypical psychosis with affective features. Neither Dr. Ara-now nor Dr. Price expressed an opinion whether the defendant was able to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law. See Commonwealth v. McHoul, 352 Mass. 544, 546-547 (1967).
The Commonwealth called three witnesses in rebuttal. None of these witnesses stated a conclusion as to whether the defendant was able to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of law, although each offered testimony that supported the Commonwealth’s position that the defendant was sane as part of the testimony.
1. The motion for required findings of not guilty. The defendant moved for required findings of not guilty, both at the close of the Commonwealth’s case2 and at the close of all the [578]*578evidence. The motions were denied. The defendant appeals, claiming that there was insufficient evidence to support jury verdicts finding him sane beyond a reasonable doubt.
In reviewing the denial of a motion for a required finding, we “must determine whether the Commonwealth’s evidence, ‘considered in its light most favorable to the Commonwealth, was sufficient to permit the jury to infer the existence of [criminal responsibility].’ ” Commonwealth v. Shelley, 381 Mass. 340, 346 (1980). In addition, “the evidence and the inferences permitted to be drawn therefrom must be ‘of sufficient force to bring minds of ordinary intelligence and sagacity to the persuasion of [sanity] beyond a reasonable doubt.’ ” Commonwealth v. Latimore, 378 Mass. 671, 677 (1979), quoting Commonwealth v. Cooper, 264 Mass. 368, 373 (1928).
The defendant stipulated to the fact that he drove the car that struck two victims, killing one of them. In its case in chief, the Commonwealth presented evidence linking the defendant’s car to the injuries and showing that one victim died as a result of injuries received when he was struck by the car. There was no error in denying the motion for a required finding of not guilty at the close of the Commonwealth’s case.
“A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law.” Commonwealth v. McHoul, supra at 546-547. When a defendant claims that he is not criminally responsible for his acts, the Commonwealth bears the burden of proving beyond a reasonable doubt that the defendant is sane. Commonwealth v. Kostka, [579]*579370 Mass. 516, 526 (1976). The defendant acknowledges that the jury is not required to accept the uncontroverted testimony of experts. Commonwealth v. Shelley, supra at 347. We have also held that the Commonwealth need not present expert evidence to prove that a defendant is sane beyond a reasonable doubt, Commonwealth v. Brennan, 399 Mass. 358, 364 (1987), and that the fact finder may infer sanity from the “facts underlying the crime and evidence of [the defendant’s] actions before and after the crime.” Commonwealth v. Cullen, 395 Mass. 225, 229 (1985).
The defendant argues that the events before the incident, the incident itself, and his actions afterwards indicate that he was not sane when he committed the crime. The defendant then asserts that he could not have formed the intent to do the act until just before he committed the crime because he did not know the victims or the area. He also states that there is no rational explanation for the commission of the crime. Finally, the defendant claims that his departure from the scene, abandonment of the automobile, and flight to New York City indicate that he did not appreciate the nature of his conduct. He points to his son’s description of the defendant’s disheveled appearance and the defendant’s attempt to strangle his son as further evidence that the defendant was acting under the compulsion of psychosis.3 We do not agree. The question of what inferences to draw from this evidence is for the jurors, not the trial judge and not this court.3
4
[580]*580After the defendant presented his case, the Commonwealth produced experts to rebut the testimony of the defendant’s experts. One of the court-appointed experts, Dr. Baxter, found no evidence of psychosis or thought disorder when she examined the defendant. The defendant told her that he had heard voices in the past, telling him to act. She testified that the defendant was able to resist these voices at times. She stated that the defendant’s description of his self-described “manic” episodes was “not typical of what people describe who have manic episodes, nor was it typical of the way that psychiatrists would diagnose a manic episode.” She explained that the defendant’s ability to function as an anesthesiologist during his past episodes, among other things, was highly unusual. Although she did conclude that the defendant suffered from mental illness, this conclusion was not based on his presentation before her but rather on the defendant’s history of hospitalization and description of psychiatric difficulties since 1953. She did consider that he might have been malingering, but did not reach any conclusion about it.
Dr. James Carpenter also testified in rebuttal. He stated that two things about the defendant’s description of the voices he heard struck him as unusual. “One was there was an inconsistency in the number of voices that he talked about. And also the nature of the hallucinations was very different from anything I had ever read about or heard about or encountered.” Dr. Carpenter testified that, when confronted with the inconsistency, the defendant “became rather pale and shaken.” Dr. Carpenter also discussed the results of various tests that he had given the defendant. He said that he could find no indications of psychosis in the defendant’s results, and that the defendant’s code on the Minnesota Multiphasic Personality Inventory test (MMPI-2)5 “was not the [581]*581description of somebody who was actively psychotic.” Dr. Carpenter said that “the character descriptions that [he] got . . . from the test material . . . had more to do with an antisocial personality and a passive dependent personality.” Dr. Carpenter explained that the code indicated that the defendant “was a person who had a tendency to over-control his hostility.” He said that the defendant’s score on one content scale, the one representing antisocial practices, was elevated.6 Dr. Carpenter then stated that “that’s one of the most frequently occurring codes among people who are incarcerated in prisons.” He then stated that the results of the tests he had administered to the defendant did not indicate that the defendant was psychotic, although they could indicate that the defendant was vulnerable to psychosis.
The last Commonwealth rebuttal witness was Dr. Frederick Kelso. He also did not reach a conclusion as to whether the defendant was criminally responsible under the McHoul test. He proffered three explanations, or models, for the defendant’s conduct. First, Dr. Kelso explained that the defendant may have been suffering from a major mental illness at the time he evaluated him. Thus, the descriptions of his thoughts and feelings would be largely accurate. Dr. Kelso rejected this model because of the atypical nature of the defendant’s descriptions. The defendant’s “disorder seemed to come upon him very rapidly. It was unusual in its nature. . . . [H]e didn’t seem to be grossly mentally ill at the time that the psychological testing was conducted.” Dr. Kelso also found noteworthy the fact that the defendant seemed to experience the voices continuously, while most people suffering from a psychosis find that the voices diminish when they engage in activity. In addition, the defendant [582]*582described the voices as coming from inside his head, whereas most people who hear voices say the voices come from outside them. The defendant’s description of more than one voice was also atypical. Finally, Dr. Kelso also suggested that both the defendant’s attempt to interpret the voices and his ability to disobey the voices were inconsistent with this model. Dr. Kelso stated “to the extent that sometimes he found himself interpreting the instructions that the voices gave him, making sense out of them in his own mind or extending them, then maybe he was actively processing the information that was going on inside his head and considering other alternative ways of behaving.”
In the next model Dr. Kelso discussed, he explained that he was concerned with the accuracy of the defendant’s “retrospective reports of his thoughts and feelings and behavior around the relevant time period.” Although Dr. Kelso often thought the defendant was being sincere, things developed in their interviews that made him question whether the defendant’s reports were completely accurate. Dr. Kelso noted that the defendant would say “I think” when he was describing much of what happened. He stated that this gave him a picture of “someone who, at some times, wasn’t entirely sure exactly what had happened and, in reconstructing it, said things consistent with that.” Dr. Kelso also questioned whether the defendant was exaggerating his experience of his disorder, citing two examples that he felt indicated that the defendant was intentionally misrepresenting his experience. The defendant sexually propositioned Dr. Kelso and Dr. Kelso said the defendant then stated, “My classification here suggests that if you report this to the court . . . that it probably won’t hurt my case.” Dr. Kelso stated that most people experiencing a psychotic episode do not draw attention to their unusual behavior. This made Dr. Kelso wonder if the defendant “had decided to proposition me, thinking that I might draw conclusions about him on account of that.” In evaluating the defendant, Dr. Kelso also considered the defendant’s statement that it was going to be very hard for him at the trial. When Dr. Kelso pursued this statement, the de[583]*583fendant stated, “They always desire remorse. It will be kind of hard to manufacture.”
The third model Dr. Kelso offered as an explanation for the defendant’s behavior was that the defendant suffered from a character or personality disorder.7 Dr. Kelso differentiated between psychosis and character disorder by saying that “[i]n a psychotic condition, a person is out of touch with reality. . . . Someone who has a character disorder . . . has got their habitual ways of looking at the world, but they’re not really out of touch with reality.” Dr. Kelso stated that the defendant did not fit precisely into any category of character disorder, but had symptoms of a number of them. Under this model, “if you assume that he’s got this character disorder and he’s just got this character disorder and he’s not psychotic, he’s not out of touch with reality, then you consider the extent to which his feelings of inadequacy and deficiency and exposure to violent ways of solving intra-personal problems, if that had anything to do with his behavior in the relevant time period.” Dr. Kelso stated that the defendant had antisocial and narcissistic traits, had exhibited some obsessive-compulsive and juvenile delinquent behavior, and had grown up in a family where violence was often used to solve problems. Dr. Kelso stated that the character disorder model explained part of the information he had received from the defendant, but not all of it.
Contrary to the dissent, the question whether to believe the experts is for the jurors, not judges. “[Jjurors are the ultimate judges of expert testimony and . . . such testimony is not conclusive . . . .” Commonwealth v. Kostka, supra at 536. Credibility is not for this court. The defendant asks that we reconsider our decision in Commonwealth v. Kostka, supra, which permits the jurors to consider as evidence the presumption of sanity. We decline to do so because there was expert testimony, which, if believed by the jurors, supported [584]*584the jurors’ conclusion that the defendant was criminally responsible.
Apart from the evidence of the crime and the inferences to be drawn therefrom, see supra at 579 and note 4, two of the Commonwealth’s experts testified that there was evidence indicating that the defendant had a personality or character disorder (a condition that does not meet the McHoul standard for lacking criminal responsibility). See note 7, supra. Dr. Carpenter stated that the records of the defendant’s psychological test scores were consistent with a personality or character disorder. See supra at 581. Dr. Kelso’s third model also explained the defendant’s behavior could result from a character or personality disorder. See supra at 583. One of the experts also opined that the unusual symptoms could be due to malingering. See supra. All the experts noted that the defendant’s symptoms were “unusual” or “atypical” and all noted inconsistencies in his descriptions of symptoms and events.
The jurors were free to believe such portions of the experts’ testimony as they deemed credible and reject the rest. “The law should not and does not give the opinions of experts on either side of the issue the benefit of conclusiveness, even if there are no contrary opinions introduced at trial.” Commonwealth v. Kostka, supra at 536, quoting Commonwealth v. Smith, 357 Mass. 168, 178 (1970). The jurors could consider the inconsistencies with the defendant’s statements to the experts in determining whether the defendant was criminally responsible. The jurors could conclude that the defendant, who had medical training in psychiatry, was attempting to manipulate the doctors with his description of his “atypical” symptoms in an effort to escape responsibility for his conduct. In sum, there was evidence which, if believed, supported the jurors’ conclusion that the defendant was criminally responsible.
2. The admission of expert testimony where the experts did not reach an opinion as to criminal responsibility. The defendant argues that it was error for the judge to admit the testimony of Drs. Baxter, Carpenter, and Kelso because none [585]*585had been able to draw a conclusion as to the defendant’s criminal responsibility under the McHoul standard.8 For the admission of expert testimony “[a] 11 that is necessary is that the subject matter be one about which special knowledge beyond that possessed by the ordinary [juror] will aid the jury in their deliberations, and that a person possessing such knowledge give opinions pertinent to the issues of the case founded upon facts which either are conceded or could warrantably be found upon other evidence.” Commonwealth v. Allen, 395 Mass. 448, 458 (1985). The experts testified as to their observations of the defendant and psychiatric explanations for the defendant’s actions. The experts simply were not able to opine whether the defendant satisfied the McHoul test for criminal responsibility. There was no error. Each expert offered theories under which the defendant would be criminally responsible. They also presented theories to support the inference that the defendant was not criminally responsible. Each expert used the McHoul standard in trying to determine the defendant’s responsibility. The experts need do no more. See Commonwealth v. Monico, 396 Mass. 793, 800 (1986). See also Commonwealth v. DeSalvo, 353 Mass. 476, 483 n.5 (1968). Psychiatric “conclusions are less important than details on which they are based.” See A.S. Goldstein, The Insanity Defense (1967). “Although experts must weigh all factors much as a jury must do, their testimony must not, in effect, usurp the jury’s functions.” Commonwealth v. DeSalvo, supra. There was no error in admitting the rebuttal testimony.9
3. The presumption of sanity under the Declaration of Rights. The defendant requests that we invalidate the instruction on the presumption of sanity.10 In Commonwealth [586]*586v. Kostka, supra at 537, we determined that the presumption of sanity did not violate the due process clause of the United States Constitution. The defendant challenges the instruction under art. 12 of the Massachusetts Declaration of Rights, arguing that, at times, the Declaration of Rights provides a defendant with broader rights than those protected under the United States Constitution. See Attorney Gen. v. Colleton, 387 Mass. 790, 796 & n.5 (1982), and cases cited. The judge correctly instructed the jurors pursuant to Massachusetts law.11
The judge instructed the jury that the Commonwealth had to prove sanity beyond a reasonable doubt. He told the jurors that the defendant did not bear the burden of proving that he was insane. He then informed the jury that most people are sane and from that, they could conclude if they so desired, that the defendant was probably sane. “The charge clearly informed the jurors that they should review all of the evidence, including expert testimony, when deciding whether to draw an inference of sanity.” Commonwealth v. Matthews, 406 Mass. 380, 391 (1990). The judge squarely placed on the Commonwealth the burden of convincing the jurors be[587]*587yond a reasonable doubt that the defendant was sane. There was no error in the jury instructions and the defendant was not entitled to any further instructions on the issue of criminal responsibility.
4. The motion for a new trial. Rule 25 (b) (2) of the Massachusetts Rules of Criminal Procedure, 378 Mass. 896 (1979), allows a judge to “set aside the verdict and order a new trial, or order the entry of a finding of not guilty, or order the entry of a finding of guilty of any offense included in the offense charged in the indictment or complaint.” The defendant argues that the judge erred in not granting his motion under rule 25 (b) (2), asserting that the jury’s verdict was against the weight of the evidence. We disagree.
We review the judge’s decision only to determine whether he “abused his discretion or committed an error of law.” Commonwealth v. Gaulden, 383 Mass. 543, 557 (1981). In Commonwealth v. Cullen, 395 Mass. 225, 231 n.4 (1985), we suggested that a judge facing a motion for new trial “should consider such factors as the defendant’s prior history of, and hospitalization for, mental illness, and the strength of the Commonwealth’s circumstantial evidence of sanity, including the testimony of lay witnesses, as well as the absence of expert testimony on behalf of the Commonwealth.”
The defendant asserts that we have granted motions for new trial in prior cases similar to, or less compelling than his, and that he therefore is entitled to a new trial. We do not agree.12 For example, in Commonwealth v. Guiliana, 390 Mass. 464, 468 (1983), all of the experts agreed that the defendant was not criminally responsible for his conduct because he lacked “both substantial capacity to conform his conduct to the requirements of the law, and substantial capacity to appreciate the wrongfulness of his conduct.” The [588]*588Commonwealth presented no evidence to support its theory that the defendant’s actions were the result of the voluntary ingestion of drugs. Id. at 469-470.
The defendant suggests that, as a matter of law and fairness, he is entitled either to required findings or a new trial. The defendant’s suggestion essentially amounts to a request that we substitute our judgment for that of jurors in cases in which criminal responsibility is the main issue. We reject that suggestion. “[Ujnder our legal system, the responsibility for stating and explaining the law is allocated to the judge, and the duty of deciding questions of fact and of applying the law to the facts is given to the jury.” Commonwealth v. Canon, 373 Mass. 494, 515 (1977) (Abrams, J., dissenting), cert. denied, 435 U.S. 933 (1978). The defendant’s argument minimizes the important role of jurors in the criminal justice system.
Judgments affirmed.