dissenting:
I agree with the conclusion reached by the majority, in Parts A and B of its opinion, that the trial court erred both in excluding from evidence the Physicians’ Desk Reference and package insert for Tobramy-cin, and in improperly limiting the testimony of Garvey’s pharmacology expert, Dr. Tice. Although I also agree with its conclusion in Part C that the trial court properly ordered redaction of the diagnoses of tinnitus contained in the treating physicians’ reports, I am of the opinion that the court erred in preventing Garvey’s OB/GYN expert, Dr. Criares, from mentioning these diagnoses during his own testimony, a ruling which the majority does not discuss. More fundamentally, I think the erroneous evidentiary rulings here went to the heart of the standard of care issue, and very nearly eviscerated Garvey’s case; I do not, therefore, share the majority’s confidence that the judgment of the jury was not swayed by the' errors. I would not find these errors harmless.
I
With regard first to the reports of Drs. Nager and Burch, two non-testifying physicians who had treated Garvey, these reports were offered in evidence by Garvey as records relied upon by her expert, Dr. Criares, in formulating his expert opinion.1 The court excluded Dr. Nager’s report entirely, and ordered Garvey to redact from Dr. Burch’s reports any diagnoses of tinnitus contained therein. The court reasoned that these diagnoses amounted to independent expert opinions on what was one of the ultimate issues of the lawsuit, and should not be presented to the jury without being subjected to cross-examination. The court also ordered Garvey’s counsel to instruct Dr. Criares not to make mention during his testimony of the other physicians’ diagnoses which the court had ordered excluded or redacted from the records.
The proffered purpose of offering the treating physicians’ diagnoses was to “test the validity of the basis upon which ... [Dr. Criares’] expert opinion rests,” Smith v. United States, 318 A.2d 891, 893 (D.C. 1974), rather than as substantive proof that Garvey had tinnitus. Although a contrary ruling would have been sustainable in my view, I cannot say that the trial court erred in concluding that sending these diagnoses to the jury room would sever their connection with Dr. Criares’ testimony, upon which he could be cross-examined. The trial court could properly conclude that even with limiting instructions, the jury would likely view these diagnoses in the jury room as additional independent diagnoses of tinnitus, equal in weight to that of Dr. Criares. As such they would become conclusions unattached to expert testimony and not subject to cross-examination. Cf 4 J. Weinstein & M. Berger, Weinstein’s Evidence II 803(18)[02], at 803.329-330 (1985) (explaining why under Fed.R.Evid. 803(18), learned treatises may only be read into evidence). With regard to the deletion of these diagnoses from the medical records, then, I share the majority’s view that the trial court did not err in concluding that the jury should not have before it what “would *1150have amounted to admitting two additional expert opinions on an ultimate issue of the case without benefit of cross-examination on the issue.” Maj.Op. at 1148.
However, the rationale for deleting the diagnoses from the medical records did not justify the court’s order that Dr. Criares not mention the diagnoses during his testimony. The majority does not address this ruling, which is, in my view, erroneous. The law of this jurisdiction clearly allows the expert to base his opinion on reports not in evidence, if of a type customarily relied upon in the practice of his profession. L.C.D. v. District of Columbia ex rel. T.-A.H.D., 488 A.2d 918, 921 n. 8 (D.C. 1985); Fed.R.Evid. 703; Jenkins v. United States, 113 U.S.App.D.C. 300, 304-05, 307 F.2d 637, 641-42 (1962) (en banc). The expert may disclose, explain, and be questioned upon those reports. Smith, supra, 318 A.2d at 893; Brown v. United States, 126 U.S.App.D.C. 134, 142, 375 F.2d 310, 318 (1966), cert. denied, 388 U.S. 915, 87 S.Ct. 2133, 19 L.Ed.2d 1359 (1967); Smith v. United States, 122 U.S.App.D.C. 300, 304-05 & n. 7, 353 F.2d 838, 842-43 & n. 7 (1965), cert. denied, 384 U.S. 974, 86 S.Ct. 1867, 16 L.Ed.2d 684 (1966); see also United States v. Sims, 514 F.2d 147, 148 & 149-50 (9th Cir.), cert. denied, 423 U.S. 845, 96 S.Ct. 83, 46 L.Ed.2d 66 (1975); S. Saltzburg & K. Redden, Federal Rules of Evidence Manual 671 (4th ed. 1986).2 Such evidence is not admissible for its truth, but rather to explain the basis for the. expert opinion. Smith, supra, 122 U.S. App.D.C. at 303 n. 4 & 304-05, 353 F.2d at 841 n. 4 & 842-43; Sims, supra, 514 F.2d at 149-50; Saltzburg & Redden, supra, at 671.
Physicians habitually rely upon the diagnoses of other physicians in making their own diagnoses and/or treating their patients. In Smith, supra, 318 A.2d at 893, the government’s expert psychologist testified as to a diagnosis similar to his own made by other hospital staff at a staff conference which the expert had not attended. The appellant alleged that conclu-sional psychiatric opinions were inadmissible when the person rendering the opinion is not present for cross-examination. Though there, as here, the other staff’s diagnosis concerned the ultimate issue to be decided (in that case, insanity), we indicated, citing the federal circuit court decisions in Brown, Smith, and Jenkins, supra, that admission of this testimony was proper.
Dr. Criares should have been permitted to testify as to the diagnoses contained in the treating physicians’ reports.3 The fact that the non-testifying doctors had since changed their opinions was not a basis for excluding this testimony; defendants could have made this fact known through cross-examination of Dr. Criares, or by calling these doctors to testify as witnesses on defendants’ own behalf.
II
My more fundamental disagreement with the majority concerns its assessment of the effect of the erroneous evidentiary rulings upon Garvey’s substantial rights. D.C. Code § 11-721(e) (1981); Giles v. United States, 432 A.2d 739, 746 (D.C.1981). In my view, the majority has mistaken the degree to which the information erroneously excluded by the trial court was “placed before the jury through another witness or in a different form.” Maj.Op. at 1148.
The PDR and package insert contained detailed information on the recommended dosage, monitoring, duration of treatment, contraindications, and side-effects of Tobra-mycin, information “not only admissible but .essential” to determining the standard of care in the use of the drug. Mueller v. Mueller, 88 S.D. 446, 221 N.W.2d 39, 43 (1974). The jury was not permitted to see the manufacturer’s information. The ma*1151jority suggests that this information was substantially presented to the jury through Garvey’s other experts. I disagree.
Dr. Tice, though permitted to describe what the PDR and package inserts are, how they are compiled or produced, and the type of information contained in them, was never in any way permitted to testify directly as to the actual information contained in the PDR and package insert about Tobramycin. The majority is perhaps comforted by the fact that Dr. Tice, near the end of his testimony, answered generally that the PDR contained information about which he had testified. I find this indirect, non-specific reference to the information contained in the PDR a very poor substitute for the document itself. Besides, the majority itself concedes that the information about which Dr. Tice testified was itself severely restricted by the trial court, omitting such essential information as the proper dosage of the drug, its side-effects and the propriety of monitoring the drug's effects through the use of blood tests. Maj. Op. at 1147; see infra at 1152.
Neither did the information contained in the PDR and package insert come in through the testimony of Dr. Gerber, Garvey’s third witness (and also one of the defendants). Dr. Gerber was permitted to testify only that the PDR and package insert provide information about recommended dosage and duration of treatment; at no time did he testify as to what that information actually was. Garvey’s attempt to elicit such testimony was objected to, and the objection sustained.
The actual information contained in the PDR and package insert came in only through Dr. Criares.4 Dr. Criares was a manifestly weak expert witness.5 Of course, Garvey was not entitled to have a star expert witness. But she was entitled to have the manufacturer’s data entered into evidence, and its exclusion was error. We “must take account of what the error meant to [the jury], not singled out and standing alone, but in relation to all else that happened.” Kotteakos v. United States, 328 U.S. 750, 764, 66 S.Ct. 1239, 1248, 90 L.Ed. 1557 (1946). Dr. Criares’ inadequacy as a witness is an aspect of the total setting of the record which must be considered. Had the PDR and insert been entered in evidence as they should by rights have been, the jury would have had before it strong evidence of standard of care in the administration of Tobramycin, undiminished by Dr. Criares’ ineffectiveness as a witness. The independent evidence of standard of care would, in turn, have lent authority to Dr. Criares’ opinion that Garvey was treated negligently. Even if these materials were not admitted, allowing Dr. Tice to testify about their contents would similarly have aided Garvey on the standard of care issue and bolstered Dr. Criare’s opinions; but, of course, Dr. Tice was silenced on the PDR and package insert as well. See supra at 1150.
Garvey was entitled to show the jury in black and white the manufacturer’s data on the drug, information which was prima facie evidence of the proper standard of care. See Maj.Op. at 1145-1146 and cases cited.6 Instead, as a result of the trial *1152court’s rulings, this information was presented only indirectly, briefly, and incompletely to the jury, in a manner bounded by the credibility of a hired expert with the “bare minimum” of credentials.
The negative effects of the PDR/package insert rulings on Garvey’s ability to establish the standard of care were compounded by other rulings as to Dr. Tice’s testimony. Perhaps the jury’s inability to see the manufacturer’s information, or hear it through the mouth of Dr. Tice, might have been compensated for had Dr. Tice been permitted to testify from his own knowledge as to the proper standard of care in the administration of the drug. He was allowed to testify about its possible side effects and the proper frequency of monitoring; but in a series of erroneous rulings, his proffered testimony as to the most important issues — indications for the use of Tobramycin, proper dosage and duration of treatment, the propriety of monitoring treatment through blood tests, and the effects of the drug on Garvey — was consistently excluded. See Maj.Op. at 1147.
In short, the erroneous evidentiary rulings had the effect of substantially depriving the jury of the testimony of one expert (Dr. Tice) on the proper standard of care, and entirely removing from it independent evidence of standard of care which Garvey was entitled to put before it (the PDR and package insert). Garvey’s evidence on the proper administration of the drug was thus reduced to a few minutes of testimony by a weak witness with no independent support.
When one further considers the exclusion from evidence of a treating physician’s diagnosis of tinnitus, it seems that the trial court could not have done more to debilitate Garvey’s expert testimony. The jury should have been permitted this information to test the bases of Dr. Criares’ opinions. See supra at 1150. The concurring diagnosis of a physician who had actually treated Garvey would have lent a firmer basis to Dr. Criares’ opinions.
In my opinion, this is a case in which it is impossible to say, “with fair assurance, after pondering all that happened without stripping the erroneous action from the whole, that the judgment was not substantially swayed by the error_” Kotteakos, supra, 328 U.S. at 765, 66 S.Ct. at 1248. I would reverse and remand for a new trial.
. It appears that Drs. Nager and Burch were not called to testify for Garvey because they would not say with a reasonable degree of medical certainty that she had tinnitus or, if she did, that it was caused by the Tobramycin.
. In Smith, supra, 122 U.S.App.D.C. at 303, 353 F.2d at 841, the circuit court permitted a portion of a psychiatric report relied upon by an expert to be read into evidence.
. A limiting instruction would have been appropriate to explain to the jury that this evidence was admitted to explain the basis of the expert’s opinion, not as substantive evidence of tinnitus. Sims, supra, 514 F.2d at 149-50; Saltzburg & Redden, supra, at 671.
. Dr. Criares briefly testified as to the possible side-effects of Tobramycin described in the PDR and package insert, and the proper dosage and duration of treatment recommended therein. However, he never testified about the PDR’s warnings as to monitoring, an important issue in the case. (Garvey contended that she received only two blood tests, the last being eight days prior to the termination of her 14-day treatment.)
. In his voir dire conducted in the presence of the jury, Dr. Criares stated that although employed at a psychiatric institution in Bronx, New York where he administered gynecological and obstetrical care to institutionalized patients, he had not delivered a baby, performed surgery, or admitted any patient to a hospital for the past six to eight years. He could identify no text in his office to which he referred. He could not, without the help of cross-examining counsel, name any of the aminoglycosides, the genre of drug to which Tobramycin belongs. He had no specialized training in infectious diseases, one area of expertise for which he was offered as an expert. Ruling that he was qualified as an expert witness, the trial judge nevertheless stated that Dr. Criares had the “bare minimum” of credentials.
.The jury itself felt a need for this information, as evidenced by its note to the trial judge, during the course of its deliberations, requesting a copy of the PDR reference on Tobramycin and *1152the package insert. The court instructed the jury that it could not provide them with material which had not been admitted in evidence,