Appellant relied solely upon the defense of insanity in a jury trial which culminated in his conviction for housebreaking with intent to commit an as.-sault, assault with intent to rape, and assault with a dangerous weapon. He alleges that the District Court erred in (1) determining his competency to stand trial, (2) excluding diagnostic opinions of two defense psychiatrists on the ground that their opinions were without “proper basis,” (3) instructing the jury to disregard the testimony on three defense psychologists that appellant had a mental disease or defect on the ground that “a psychologist is not competent to give a medical opinion as to a mental disease or defect,” and (4) depriving him of a fair trial by conducting a lengthy and disparaging examination of some expert witnesses.
7. The Facts
The record discloses the following pertinent information. After indictment, appellant was committed to the District General Hospital for a mental examination on September 4, 1959, to determine his competency to stand trial and his condition at the time of the alleged offense.1 Appellant was given a series of psychological tests on October 20 and 22, 1959, by staff psychologists under the supervision of the Chief Psychologist, Dr. Bernard I. Levy. Appellant scored 63, high moron, on the I.Q. section of the tests. He was also interviewed three or four times by Dr. Richard Schaengold, Assistant Chief Psychiatrist. Appellant’s test performance and his “dullness and inability to relate correctly” led Dr. Schaengold to consider and reject the possibility of undifferentiated psychosis in favor of a diagnosis of mental defect: a basic, unchanging deficiency in brain function.2 His findings were confirmed by Dr. Mary V. McIndoo, District General’s Chief Psychiatrist, on the basis of interviews on November 23, 24 and 25, and a review of appellant’s history and test results. By letter of November 25, 1959, signed by Dr. Schaengold and countersigned by Dr. Mclndoo, the District Court was advised that appellant was “suffering from an organic brain defect resulting in mental deficiency and impaired *640judgment. He is, therefore, psychotic, incompetent, and incapable of participating in his own defense.” Appellant was adjudicated incompetent to stand trial on the basis of this report and was committed to “Saint Elizabeths Hospital until he is mentally competent to stand trial pursuant to Title 24, Section 301, District of Columbia Code, 1951 Edition, as amended August 9, 1955.”
At St. Elizabeths, Dr. Lawrence Tir-nauer, a staff psychologist, administered another battery of psychological tests on February 25 and March 2, 1960, in which appellant scored 74 on the I.Q. section. Dr. Tirnauer concluded that appellant was suffering from schizophrenia. Thereafter Dr. David J. Owens of St. Eliza-beths interviewed appellant several times, “probably [for] fifteen or twenty minutes,” and saw him at a staff conference on October 3, 1960. Dr. Owens found no evidence of mental disease or defect. He classified appellant as “a borderline intelligence.” Dr. William G. Cushard, another psychiatrist at St. Elizabeths, who saw appellant at the staff conference, reviewed the test reports and agreed with Dr. Owens’ findings. Dr. Margaret Ives, Chief Psychologist at St. Elizabeths, was also present at the staff conference. Subsequently, she reviewed Dr. Tirnauer’s test results and appellant’s past history and administered one part of a six-part Szondi profile test. She agreed with Dr. Tirnauer that appellant “had a mental illness by name of schizophrenia.”
Ten days later, the Acting Superintendent of the Hospital notified the District Court that “it has been determined that he [appellant] is, at this time, mentally competent to stand trial and to consult with counsel and assist properly in his own defense. He is not suffering from mental disease * * *. Although he is not suffering from mental deficiency, he has only borderline intelligence.” Upon appellant’s objection to this report, the court conducted a hearing on November 4, 1960, wherein appellant was found competent and ordered to stand trial.
In preparation for their testimony at trial, Drs. Mclndoo and Schaengold noted the later and different diagnosis and the apparent change in appellant’s I.Q. reported by the St. Elizabeths psychologists. They requested Dr. Levy of their staff to re-test appellant in order to reconsider their diagnoses that he was mentally defective on June 10, 1959, the date of the alleged offenses. This time appellant scored 90 on the I.Q. test, an improvement inconsistent with mental defect. In reporting this result, Dr. Levy, who had previously been unable to make a diagnosis, concluded that upon review of all test data appellant “is psychotic and schizophrenic.” Considering this report in the light of the hospital record and “reports” from St. Elizabeths, Drs. Mclndoo and Schaengold revised their previous diagnoses without seeing appellant again. Dr. Mclndoo concluded that appellant was schizophrenic, and Dr. Schaengold diagnosed his condition as undifferentiated psychosis.
II. Admissibility of the Psychiatrists’ Opinions
The trial court, sua sponte, excluded the revised diagnoses of Drs. Mclndoo and Schaengold and instructed the jury to disregard testimony of the three defense psychologists that appellant had a mental disease when he committed the crimes charged.
We discuss first the exclusion of Dr. Schaengold’s testimony. After questioning him at great length about the basis of his revised opinion, the court ruled: “All I will allow is that in his opinion on June 10, 1959 [the date of the alleged offenses], the defendant was mentally defective”; it excluded Dr. Schaengold’s later diagnosis of mental illness because “there isn’t any testimony here that is based on any proper evidence that he was suffering from a mental disease. I am not going to allow it on the basis of a report of a psychologist.” The court gave no further explanation.
The Government suggests that the ruling rests on the familiar principle that an expert witness’ knowledge of “basic *641facts” must be adequate to support his conclusion.3 It urges that the later psychological reports could not provide Dr. Schaengold with such information, “absent a personal re-examination of appellant,” since thirteen months had elapsed between his personal examination of appellant and his revised diagnosis. The proposition seems to be that a psychiatric witness may not rely on psychological test reports unless he has considered them in conjunction with a contemporaneous personal examination. We are aware of no authority for such a rigid and artificial stricture.4
Dr. Schaengold, whose expert qualifications were unquestioned, testified that he could arrive at a valid diagnosis on the basis of an earlier examination and later test reports. The court must be deemed to have rejected this statement. We find no basis for such action. We think it clear that Dr. Schaengold’s ability to make the revised diagnosis without conducting a personal re-examination presents a question for the consideration of the jury, under appropriate instructions, in assessing the weight of his testimony and not a question for the court upon which it may rest exclusion of the diagnosis as a matter of law.
It is at least as likely, however, that the court predicated its ruling on cases which bar an expert's opinion based upon facts not in evidence unless it is derived solely from his own observations.5 But we agree with the leading commentators 6 that the better reasoned authorities admit opinion testimony based, in part, upon reports of others which are not in evidence but which the expert customarily relies upon in the. practice of his profession.7 The Wisconsin Supreme Court has forcefully stated the policy underlying the application of this rule to medical testimony:
“In order to say that a physician, who has actually used the result of * * * tests in a diagnosis * * * may not testify what that diagnosis was, the court must deliberately shut its eyes to a source of information which is relied on by mankind generally in matters that .involve the health and may involve the life of their families and of themselves — a source of information that is essential that the court should possess in order that it may do justice between these parties litigant.
“This court * * * will not close the doors of the courts to the light which is given by a diagnosis which all the rest of the world accepts and acts upon, even if the diagnosis is in part based upon facts which are not established by the sworn testimony in the case to be true” [Sund-*642quist v. Madison Ry., 197 Wis. 83, 221 N.W. 392, 393 (1928).]
The record in this case confirms the well-known practice of psychiatrists of relying upon psychologists’ reports in aid of diagnosis.8 And it shows that Dr. Schaengold’s changed diagnosis did not rest solely on the later test reports which were not in evidence when he testified,9 but also upon his own earlier examination.10 This diagnosis was “the type of clinical opinion he is accustomed to form and to rely upon in the practice of his profession. * * * Though [his] conclusions were not mathematically demonstrable certainties, neither were they mere conjectures, suspicions or hunches.” Blunt v. United States, 100 U.S.App.D.C. 266, 275, 244 F.2d 355, 364 (1957).
It follows from the foregoing that the court’s sua sponte exclusion of Dr. Schaengold’s testimony concerning his changed diagnosis was error.11 Since the exclusion was clearly prejudicial, the conviction must be reversed for a new trial.12
Appellant also objects to the similar exclusion of Dr. Mclndoo’s revised diagnosis. She testified that the later tests induced her to change her opinion. But when the court, in very extensive questioning, made clear its view barring reliance upon psychological test reports, she stated that she “did not have a medical opinion about the new diagnosis.” At one point she said, “I’m strictly confused now.” Later the following occurred:
The Court: Would you express an opinion as to a person’s mental condition on the basis of a report given to you by a psychologist ?
The Witness: I do, Your Hon- or, very frequently.
The Court: Without even seeing the patient ?
The Witness: In most cases I do see the patient. This person I had seen. He was showing certain signs and symptoms. I made a wrong diagnosis. The suggested diagnosis from a psychologist explains my wrong diagnosis.
Since the new trial required by the exclusion of Dr. Schaengold’s testimony will afford an opportunity for clarification of Dr. Mclndoo’s testimony in light of our earlier discussion, we think it unwise to engage in the speculation required to resolve the meaning of her testimony at the trial under review. Hence we refrain from deciding whether the court erred in excluding her opinion.
III. Admissibility of the Psychologists’ Opinions
The next assignment of error we discuss concerns the court's instruction to the jury to disregard testimony of *643three defense psychologists that appellant had a mental disease when he committed the crimes charged. Although appellant failed to object to this instruction, we consider it because it presents a question which is likely to arise upon a new trial.13
The first psychologist, Dr. Tirnauer, administered a battery of tests to appellant, studied his case history, and concluded he had been suffering from schizophrenia when he committed the crimes. In his opinion, the disease and the crimes were “related.” The second psychologist, Dr. Margaret Ives, had reviewed Dr. Tirnauer’s test results, had seen appellant at a staff conference, and had administered part of a Szondi profile test. She stated that appellant was suffering from schizophrenia and that his crimes were the product of the disease. The third psychologist, Dr. Levy, interpreted test results obtained by members of the District General staff in October 1959, and administered two additional tests shortly before trial. He testified that defendant had been suffering from schizophrenia on June 10, 1959, but could give no opinion concerning the relationship between the illness and the crimes. At the conclusion of the trial the court instructed the jury:
“A psychologist is not competent to give a medical opinion as to a mental disease or defect. Therefore, you will not consider any evidence to the effect that the defendant was suffering from a mental disease or a mental defect on June 10, 1959, according to the testimony given by the psychologists.”
The trial court apparently excluded these opinions because psychologists lack medical training. We agree with the weight of authority, however, that some psychologists are qualified to render expert testimony in the field of mental disorder.14
We begin by placing this problem in the context of the considerations governing the reception of expert testimony.
“An observer is qualified to testify because he has firsthand knowledge which the jury does not have of the situation or transaction at issue. The expert has something different to contribute. This is a power to draw inferences from the facts which a jury would not be competent to draw. To warrant the use of expert testimony, then, two elements are required. First, the subject of the inference must be so distinctively related to some science, profession, business or occupation as to be beyond the ken of the average layman, and second, the witness must have such skill, knowledge or experience in that field or calling as to make it appear that his opinion or inference will probably aid the trier in his search for truth. The knowledge may in some fields be derived from reading alone, in some from practice alone, or as is more commonly the case, from both. [McCormick, Evidence § 13 (1954), citing authorities.]”
The test, then, is whether the opinion offered will be likely to aid the trier in the search for truth. In light of that purpose, it is hardly surprising that courts do not exclude all but the very best kind of witness. See 2 Wigmore, Evidence § 569 (3d ed. 1940). Accord: Fightmaster v. Mode, 31 Ohio App. 273, 167 N.E. 407 (1928). Thus a general practitioner may testify concerning matters within a medical specialty if his education or experience, or both, involves demonstrable knowledge of the subject. Sher v. DeHaven, 91 U.S.App.D.C. 257, *644199 F.2d 777, 36 A.L.R.2d 937 (1952), cert. denied, 345 U.S. 936, 73 S.Ct. 797, 97 L.Ed. 1363 (1953); 2 Wigmore, op. cit. supra. Nor need a skilled witness on a medical subject be duly licensed to practice medicine. Ibid. The general rule is that “anyone who is shown to have special knowledge and skill in diagnosing and treating human ailments is qualified to testify as an expert, if his learning and training show that he is qualified to give an opinion on the particular question at issue.” “It is not essential that the witness be a medical practitioner.” 32 C.J.S. Evidence § 537 (1942). Thus, non-medical witnesses who have had experience in electrical work may testify to the effects of electrical shock upon the human body. Vessels v. Kansas City Light & Power Co., 219 S.W. 80 (Mo.Sup.Ct.1920); Blakeney v. Alabama Power Co., 222 Ala. 394, 133 So. 16 (1931). Optometrists, whose training includes instruction in the symptoms of certain eye diseases, may testify to the presence of cataract discovered in the course of fitting glasses, Jackson v. Waller, 126 Conn. 294, 10 A.2d 763 (1940), and to the effect of a scar upon vision. Black Starr Coal Corp. v. Reeder, 278 Ky. 532, 128 S.W.2d 905 (1939). A toxicologist has been permitted to testify to the effect of oxalic acid, a poison, upon the human eye. Reynolds v. Davis, 55 R.I. 206, 179 A. 613 (1935). The kinds of witnesses whose opinions courts have received, even though they lacked medical training and would not be permitted by law to treat the conditions they described, are legion. The principle to be distilled from the cases is plain: if experience or training enables a proffered expert witness to form an opinion which would aid the jury, in the absence of some countervailing consideration, his testimony will be received.
Suggesting the diagnostic category into which an accused’s condition fits, and relating it to his past behavior require skill far in excess of that possessed by laymen. Lest the jury be misled into relying on opinions which are not based upon relevant learning and experience, we must examine the reality behind the title “psychologist.” Many psychologists may not qualify to testify concerning mental disease or defect. Their training and experience may not provide an adequate basis for their testimony. Some psychologists, for example, teach and engage in theoretical research in fields unrelated to the diagnosis and treatment of mental disease. Others are employed in personnel administration, still others advise industry on problems of employee morale. See Western Personnel Institute, Opportunities for Psychologists, Psychiatrists, Psychiatric Social Workers 8-10 (1958); Daniel and Louttit, Professional Problems in Psychology 250-52, 297 (1953). Such experience does not ordinarily provide the skill essential to offer expert testimony concerning mental disorders. Cf. Albee, Mental Health Manpower Trends 116 (1959). Some psychologists, moreover, have had no post-graduate instruction. Id. at 121-22.
On the other hand, the Ph.D. in Clinical Psychology involves some — and often much — training and experience in the diagnosis and treatment of mental disorders. Typically, candidates are trained, inter alia, in general psychology, theory of personality and psychodynamics, psychopathology, diagnostic methods, therapeutic techniques, selected aspects of physiology and anatomy, and clinical methods. A one-year internship in a mental hospital is required for this degree.15 After graduation, many clinical psychologists administer and interpret diagnostic tests which elicit the patient’s intellectual level, defenses, personality structure, attitudes, feelings, thought and perceptual processes. See 1 Rapa-*645port, Diagnostic Testing 7-9 (1945). In many institutions and clinics their reports, which regularly include opinions concerning the presence or absence of mental disease or defect,16 are important aids to psychiatrists who customarily have the final responsibility for diagnosis. Some psychologists, moreover, regularly administer psychotherapy and related non-organic therapies in the treatment of certain types of mental disorders.17
The determination of a psychologist’s competence to render an expert opinion based on his findings as to the presence or absence of mental disease or defect must depend upon the nature and extent of his knowledge. It does not depend upon his claim to the title “psychologist.” And that determination, after hearing,18 must be left in each case to the traditional discretion of the trial court subject to appellate review.19 Although there are no statutory criteria for licensing psychologists in the District of Columbia to assist trial courts,20 the American Psychological Association’s list of approved graduate training programs provides some guidance. When completion of such training is followed by actual experience in the treatment and disagnosis of disease in association with psychiatrists or neurologists, the opinion of the psychologist may properly be received in evidence.
Some graduate clinical psychologists, moreover, are certified by the American Board of Examiners in Professional Psychology.21 Certification, which indicates exceptional professional competence, is awarded upon completion of written and oral examinations in, mter alia, diagnosis and treatment.22 Applicants must have four years, acceptable professional experience and must present credentials, including a sample of their work and letters of recommendation, showing sufficient professional achievement to warrant further examination.23 The purpose of Board certification is to identify and evaluate psychologists at an advanced professional level. If the postdoctoral experience required for certification has included substantial experience in a hospital or clinical setting in association with psychiatrists or neurologists, clinical psychologists who are diplomates of the American Board of Examiners in Professional Psychology should ordinarily qualify as expert witnesses.
We need not decide whéther the three psychologists who testified for the defense at the trial under review were qualified to offer expert opinions since they may not be called to testify at *646the retrial.24 We hold only that the lack of a medical degree, and the lesser degree of responsibility for patient care which mental hospitals usually assign to psychologists, are not automatic disqualifications. Where relevant, these matters may be shown to affect the weight of their testimony, even though it be admitted in evidence. The critical factor in respect to admissibility is the actual experience of the witness and the probable probative value of his opinion. The trial judge should make a finding in respect to the individual qualifications of each challenged expert. Qualifications to express an opinion on a given topic are' to be decided by the judge alone.25 The weight to be given any expert opinion admitted in evidence by the judge is exclusively for the jury.26 They should be so instructed.
IV. Competency to Stand Trial
Another ground urged for reversal is that the November 4 order adjudicating appellant competent to stand trial was not authorized by D.C.Code § 24-301(b). That section provides, in substance, that when an accused person "is restored to mental competency” and when the hospital superintendent so certifies, the court may enter an adjudication of competence “unless the accused or the Government objects, in- which event, the court, after hearing without a jury, shall make a judicial determination of the competency of the accused to stand trial.” Emphasis supplied. Here, the Superintendent did not certify that appellant’s competency had been “restored” but rather that appellant “is, at this time, mentally competent.” Upon appellant’s objection, the court conducted a hearing in which Dr. David J. Owens, a hospital psychiatrist, testified that appellant was not a mental defective, and that there was no indication of organic brain injury or mental illness. His testimony clearly implied that appellant had been competent when committed. Appellant presented no evidence, and the court adjudicated him “mentally competent to stand trial.”
Appellant contends that the statute applies only to cases of “restored competency” and cannot be invoked, as here, to set aside an original adjudication of incompeteney. He argues that an adjudication of .“restored competency” was precluded by the evidence at the hearing which showed only that appellant’s condition was unchanged.
Clearly the determination of appellant’s eligibility to stand trial may be established by a finding of “restored competency” or a finding that he never was incompetent. Assuming, arguendo, as appellant implies, that a proceeding to set aside the original adjudication of incompetency is required, we think the substance of such proceeding was provided by the hearing conducted below. Appellant does not claim that he was surprised or otherwise prejudiced by the Government’s evidence that he never was incompetent.
Appellant’s remaining contention concerns the conduct of the trial court in questioning certain expert witnesses. Since this issue may not arise upon the new trial, we do not consider it.
The judgment of conviction is reversed and the case is remanded to the District *647Court for further proceedings in accordance with this opinion.27
Reversed and remanded for a new trial.*
. See generally Winn v. United States, 106 U.S.App.D.C. 133, 270 F.2d 326 (1959).
. Durham v. United States, 94 U.S.App.D.C. 228, 241, 214 F.2d 862, 875, 45 A.L.R.2d 1430 (1954).
. Toho Bussan Kaisha, Ltd. v. American. Pres. Lines, Ltd., 265 F.2d 418, 76 A.L.R.2d 1344 (2d Cir. 1959); Haug v. Grimm, 251 F.2d 523 (8th Cir. 1958). The Government cites United States v. Alker, 260 F.2d 135, 155 (3d Cir. 1958), cert. denied, 359 U.S. 906, 79 S.Ct. 579, 3 L.Ed.2d 571 (1959), where the proposition appears as dictum.
The Government’s reliance upon Blunt v. United States, 100 U.S.App.D.C. 266, 275, 244 F.2d 355, 364 (1957); and Carter v. United States, 102 U.S.App.D.C. 227, 236, 252 F.2d 608, 617 (1957), is misplaced since our discussion of the absence of detailed testimony concerning the underlying basis for the psychiatrists’ opinions related to the weight of the testimony and not its admissibility.
. Cf. Williams v. United States, 104 U.S.App.D.C. 277, 278, 261 F.2d 743, 744 (1958), where we held that a new trial would be required if appellant could establish his allegations concerning newly discovered evidence of changed psychiatric opinion “without additional examination of appellant.”
. E. g., People v. Black, 367 Ill. 209, 10 N.E.2d 801 (1937) (alternative holding); Equitable Life Assur. Soc’y v. Kazee, 257 Ky. 803, 79 S.W.2d 208 (1935) (dictum). See generally McCormick, Evidence § 15 (1955).
. McCormick, Evidence § 15 (1955). See 3 Wigmore, Evidence § 688 (3d ed. 1940).
. Taylor v. Monongahela Ry., 155 F.Supp. 601, 604 (W.D.Pa.1957), aff’d per curiam, 256 F.2d 751 (3d Cir. 1958); Sund-quist v. Madison Ry., 197 Wis. 83, 221 N.W. 392 (1928); Schooler v. State, 175 S.W.2d 664 (Tex.Civ.App.1943).
. Hidden v. Mutual Life Ins. Co., 217 F.2d 818, 821 (4th Cir. 1954); Scheflen, The Psychologist as a Witness, 32 Pa.Bar Ass’n Q. 329, 333 (1961). See McDonald, Psychiatry and the Criminal 162 (1958).
. Such reliance would amount to offering an opinion of another in violation of the hearsay rule. Cf. McCormick, Evidence § 15 (1955).
. Dr. Schaongold testified that he considered undifferentiated psychosis a possibility when he first examined appellant. The improvement in appellant’s I.Q. scores was inconsistent with mental defect, and induced Dr. Sehaengold to abandon that diagnosis in favor of undifferentiated psychosis which was consistent both with his earlier clinical observations and the later test reports.
An opinion so formulated is admissible. Cf. Williams v. United States, supra note 4. Any infirmity arising out of Dr. Schaengold’s failure to re-examine appellant would go to the weight and not to the admissibility of his opinion. Cf. Brill v. Mushinsky, 90 U.S.App.D.C. 132, 194 F.2d 158 (1952).
. See Hidden v. Mutual Life Ins. Co., supra note 8; Watts v. State, 223 Md. 268, 164 A.2d 334 (1960) (alternative ground).
. In holding Dr. Schaengold’s testimony admissible, we do not intimate approval of his failure to re-examine appellant. Compare Winn v. United States, 106 U.S.App.D.C. 133, 270 F.2d 326 (1959); Carter v. United States, 102 U.S.App.D.C. 227, 236, 252 F.2d 608, 617 (1957); Blunt v. United States, 100 U.S.App.D.C. 266, 275, 244 F.2d 355, 364 (1957).
. Villaroman v. United States, 87 U.S.App.D.C. 240, 184 F.2d 261, 21 A.L.R. 26 1074 (1950).
. See Hidden v. Mutual Life Ins. Co., supra note 8; Watson v. State, 161 Tex.Cr.R. 5, 273 S.W.2d 879 (1954), rev’d on other grounds on rehearing. People v. Hawthorne, 293 Mich. 15, 291 N.W. 205 (1940) (dictum); State v. Padilla, 66 N.M. 289, 347 P.2d 312, 78 A.L.R.2d 908, (1959) (dictum). See generally, Scheflen, supra note 8; Louisell, The Psychologist in Today’s Legal World, 39 Minn.L.Rev. 235 (1955).
. See Report of the Committee on Training in Clinical Psychology of the American Psychological Association, in 2 Am. Psychol. 539, 543-58 (1947). The Association certifies only those programs meeting the standards laid down in this report.
. Scheflen, supra note 8.
. See Clark, America’s Psychologists 188-205 (1957). See also Joint Commission on Mental Illness and Mental Health, Action for Mental Health 244-50 (1961).
. The court may conduct this hearing in the presence of the jury unless special circumstances warrant its exclusion.
. Cf. Pollard v. Hawfield, 83 U.S.App.D.C. 374, 170 F.2d 170 (1948), cert. denied, 336 U.S. 909, 69 S.Ct. 514, 93 L.Ed. 1073 (1949). Compare State v. Padilla, 66 N.M. 289, 347 P.2d 312, 78 A.L.R.2d 908 (1959). See also McDonald, supra note 8.
The qualification of a particular witness to testify as an expert is largely within the domain of the trial judge. Particular inquiries which may be appropriate in some cases may be inappropriate in others. The majority of this court think the matter should be left to the sound judicial discretion of the trial judge, with no more specific guidance than is contained in this opinion.
. Such statutes are in force in several states. See, e. g., Conn.Gen.Stat.Ann. §§ 20-188 to 20-191 (1960); Md.Ann.Code Art. 43 §§ 618-620, 629-636 (1957); Mich.Stat.Ann. §§ 14.677(3)-14.677(11) (Supp.1959), Pub.Acts 1959, No. 257.
. Kelley, Sanford & Clark, The Meaning of the ABEPP Diploma, 16 Am.Psychol. 132-34 (1961). Prior to 1949, the Board waived the Ph.D. or examination requirements, or both, if a candidate was judged qualified on the basis of training, professional experience and his colleagues’ endorsements. Id. at 132.
. Id. at 134, 138.
. Id. at 134.
. The trial judge might have concluded that one or more of the three defense psychologists were competent to testify as experts. All are clinical psychologists; all hold doctoral degrees from institutions approved hy the American Psychological Association; all are associated with psychiatrists and neurologists in a hospital setting in the diagnosis and treatment of mental illness. Two were chief psycholo--gists at the hospitals where they were employed, and the third had diagnosed more than a hundred patients during his three years at St. Elizabeths.
. Sher v. De Haven, 91 U.S.App.D.C. 257, 199 F.2d 777, 36 A.L.R.2d 937 (1952), cert. denied, 345 U.S. 936, 73 S.Ct. 797, 97 L.Ed. 1363 (1953).
. O’Donnell v. Geneva Metal Wheel Co., 183 F.2d 733 (6th Cir. 1950), cert. denied, 341 U.S. 903, 71 S.Ct. 612, 95 L.Ed. 1342 (1951).
. See note 19 supra.
The retirement of Senior Circuit Judge Prettyman became effective April 16, 1962. Prior thereto he concurred in the foregoing opinion and joined in the judgment entered April 12, 1962.