In this аppeal, which is here on the defendant’s application for further appellate review
(Commonwealth
v.
Schulze,
The defendant was convicted of crimes committed in the course of an attempted armed robbery of a Somerville phar *736 macy in September, 1979. The pharmаcist activated a silent alarm, and the police surrounded the premises. The defendant and an accomplice, one Queeney, held the pharmacist, one of his employees, and some customers as hostages; the defendant negotiated with the police by telephone. As time passed and tension built, the defendant demanded drugs from the pharmacist and drank various codeine cough medicines. Gradually the defendant became groggy from the effects of the drugs; the pharmacist then disarmed him; and the police entered the pharmacy and arrested the defendant and Queeney.
The defendant’s sole defense was that he lacked criminal responsibility for his acts. In circumstances we shall state more fully later in this opinion, the trial judge excluded proffered testimony from a general practitioner who had seen the defendant as a patient four days and ten days prior to the crimes. The defendant presented a qualified psychiatrist who testified that the defendant suffered from a “chronic characterologic depression” and that, at the time of the attempted robbery, the defendant was in an “acute toxic psychosis” resulting from his use of heroin earlier that day. The Commonwealth presented two psychiatrists who testified that the defendant did not lack criminal responsibility on the day of the attempted robbery. Represented by new counsel on appeal, the defendant challenges his convictions and the denial of his motion for a new trial.
The defendant called as a witness Dr. Stanley Chin, a licensed general practitioner with about thirty years’ experience, who testified that he saw the defendant as a patient on September 7, 1979, and again on September 13, 1979. 1 When defense counsel asked Dr. Chin to tell what his examination and his treatment of the defendant consisted of, the prosecutor objected and a bench conference followed. The prosecutor spoke first stating that, as he understood the defense, it relied on an acute toxic psychosis that occurred on the date of the crimes and only on that day. He said he did *737 not know what Dr. Chin could add. The following colloquy then occurred:
The judge: “What is he going to testify?”
Defense counsel: “Medical history.”
The prosecutor: “He is not even a psychiatrist.”
Defense counsel: “He is going to give an opinion as to his state those four or five days before.”
The judge: “Is this man a psychiatrist, any psychiatric history?”
Defense counsel: “Just a general practitioner, your Honor.”
The judge: “Sorry.”
Defense counsel: “He gave him medication.”
The judge: “Unless you can indicate to me he got qualifications to express an opinion as to this defendant’s mental cоndition for criminal responsibility I will not allow him to testify.”
Defense counsel: “If Your Honor pleases, with all due respect to your Honor, other evidence as to his mental responsibility — not his criminal responsibility, but his mental condition on previous occasions is admissible.”
The judge: “What is he going to testify to?”
Defense сounsel: “He will testify that he gave him one prescription, if your Honor please, one on each day for ten milligrams of Valium.”
The judge: “That’s all he’s going to testify to?”
Defense counsel: “That’s all.”
The judge: “Excluded.”
Defense counsel: “Note my objection.”
The bench conference ended, and no further questions were put to Dr. Chin.
*738 At the hearing on the defendant’s motion for a new trial, Dr. Chin was not called as a witness. The parties stipulated that, if called, Dr. Chin would testify that he examined and treated the defendant at his office on September 7 and 13, 1979, that he advised the defendant to have a psychiatric consultation, and that his diagnosis was “[depression with anxiety and manic tendencies.” Defense counsel knew the nature of this proposed testimony before trial.
The colloquy presents several problems. The final offer of proof — that Dr. Chin prescribed Valium on two occasions — does not justify reversal of the defendant’s convictions. The exclusion of that evidence, even if relevant, was not of sufficient significance to constitute prejudicial or reversible error. Such a limited view of the offer of proof, however, may not be warranted because defense counsel had indicated eаrlier that Dr. Chin would testify as to the defendant’s medical history and give an opinion as to the defendant’s “state those four or five days before.” If the offer of proof was deficient, the issue then becomes, as the defendant contended in his motion for a new trial, whether the defendant was thereby denied the effective assistance of counsel.
We agree with the judge’s comment that Dr. Chin could not testify concerning the defendant’s criminal responsibility. In this Commonwealth, in order to give an opinion on criminal responsibility, a physician must be more qualifiеd in the treatment of mental diseases and defects than a general practitioner, although he need not be a specialist in psychiatry. See
Commonwealth
v.
Boyd,
Dr. Chin could have testified at least to what he observed on the two occasions, shortly before the crime, when he saw the defendant. Under our prior cases, however, he could not have given an opinion, based on hypothetical circumstances or even basеd on his personal observations, concerning the defendant’s criminal responsibility on the days he saw the defendant or on the day of the crimes.
3
Our prior cases have not explicitly addressed whether a general practitioner who treated a defendant may tеstify as to his opinion, based on personal observation, of the defendant’s mental condition at the time he saw the defendant. Expanding on our prior opinions, we conclude that, where criminal re
*740
sponsibility is an issue at trial, a licensed physician should be allowed tо testify to his observations, diagnosis, and treatment of a defendant whom he saw within a relevant period of time prior to or after the date of the crime.
4
This conclusion is the general view of well-reasoned opinions in jurisdictions where substantially the same standard of criminаl responsibility is applied as we apply under
Commonwealth
v.
McHoul,
*741
Our inquiry does not end here. If the offer of proof properly preserved the issue for appellate consideration, we must decide whether the exclusion of that evidenсe was prejudicial error requiring reversal of the convictions and a new trial. If, alternatively, the issue was not properly preserved, we must decide whether any serious incompetency of counsel in presenting the offer of proof “likely deprived the defendant of an otherwise available, substantial ground of defence.”
Commonwealth
v.
Saferian,
The theory of the defense was that acquaintances gave the defendant heroin and the defendant, who was drunk and depressed, injected himself with the heroin. The defense argued that the heroin was an overdose but that the defendant did not know it was an overdose and that the heroin caused an “acute toxic psychosis.” The defendant’s expert testified that the defendant lacked criminal responsibility as defined in
Commonwealth
v.
McHoul,
From our review of the evidence in this case, we conclude that the admission of Dr. Chin’s testimony might have significantly affected the jury’s conclusion on the issue of criminal responsibility. Dr. Chin’s testimony, added to other evidence, could have created a reasonable doubt that the jury did not find with Dr. Chin’s testimony excluded. Dr. Chin determined, four days before the crimes, that the defendant should seek a psychiatric consultation and that the defendant was depressed “with anxiety and manic tendencies.” We cannot conclude in all fairness that the jury would not possibly have found this evidence significаnt in their consideration of the issue of criminal responsibility. Dr. Chin’s testimony would have tended to support the opinion of the defendant’s expert witness that the defendant was suffering from chronic depression. Our conclusion is not altered by the fact that the defendant’s expert witness based his opinion on his belief that the defendant lacked criminal responsibility because of an acute toxic psychosis caused by the use of drugs on the day of the crimes. The defendant was not limited to only one theory in arguing his lack of criminal responsibility. See
Commonwealth
v.
Genius,
The order denying the motion for a new trial is reversed. The judgments are reversed and the verdicts set aside. There must be a new trial. 6
So ordered.
Notes
The crimes were committed on September 17, 1979.
In
Old Colony Trust Co.
v.
DiCola,
As the Appeals Court noted
(Commonwealth
v.
Schulze,
We specifically note that we are stating a new rule and that the Appeals Court should not be faulted for adhering to our prior decisions on this subject.
Under Rule 701 of the Proposed Massachusetts Rules of Evidence and the parallel Federal rule of evidence, any witness not testifying as an ex *741 pert would be permitted to state an opinion which was rationally based on the witness’s perception and helpful to the determination of a fact in issue. The advisory committee’s note on rule 701 states that the rule “may alter present Massachusetts law which excludes lay opinion as to sanity” (except as to an attesting witness to a will and a testator’s attending physician) . The new rule we state, limited to nonexpert physicians, does not go as far.
We do not discuss other issues argued by the defendant because they are not likely to be involved at the new trial.
