concurring in the result:
The plain words of the carefully created, thoroughly reviewed, fully annotated Federal Rules of Evidence are for courts to follow, not embellish. I am perplexed by the fact that my colleagues in the majority embellish them and in dissent refuse to follow them.
The district court properly excluded expert opinion testimony that it correctly found to be substantially more prejudicial than probative. The majority per curiam approves exclusion, but does so by applying a homemade test for admissibility which not only disregards the plain meaning of the rules, but also builds in a headwind favoring exclusion of such evidence on a far broader basis than the rules permit. Judge Reavley’s dissent demonstrates that the majority ignores, in part, and modifies, in part, two of the rules (702 and 703), yet refuses to recognize that the trial court’s valid reliance on a third rule (403) requires affirmance. The confusing result of these divergent views could thwart the very reason the court took the case en banc — to light the path district courts should follow in ruling on expert opinion evidence. I hope the result will not be to cause trial judges in this circuit to think we have deprived them of their broad discretion to make fair rulings on the admissibility of such proof. The rules they are bound to follow still control.
Because the district court’s ruling under Rule 403 is fully supported by the record, I concur in the result reached by the majority-
I. RULE 702.
Rule 702 defines the basic perimeter of expert opinion evidence:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
Obviously, a medical opinion as to causation would assist the trier of fact in this highly technical scientific case. As Judge Reavley’s dissent establishes, it is equally obvious that Dr. Miller is a trained, experienced scientist who possesses specialized knowledge in toxicology and related fields. Both parts of the rule were satisfied. I agree with the district court and Judge Reavley that the summary judgment record establishes that Dr. Miller was qualified to testify as an expert under Rule 702.
The majority errs when it interprets Rule 702 to require the expert’s opinion to assist the trier of fact. That is not what the rule says. Expert opinion testimony is admissible when “scientific, technical, or other specialized knowledge will assist the *1117trier of fact to understand the evidence or to determine a fact in issue_” The advisory committee’s notes make it clear that this rule focuses any question of assistance on the nature of the jury’s factual inquiry rather than on the substance of the expert’s testimony.
II. RULE 703.
In two clear English sentences, Rule 703 addresses the permissible evidentiary bases for expert opinion evidence.
The facts or data in the particular case upon which an expert bases an opinion or inference may be those perceived by or made known to the expert at or before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence.
As with Rule 702, the majority pays scant heed to Rule 703’s plain language. The result is a confusing and internally inconsistent revision which gives almost no guidance to the district courts except to restrict the admissibility of expert opinion testimony in ways never intended by the Federal Rules of Evidence.
A. Plain Words, Plain Meaning.
The first sentence of Rule 703 allows an expert to base an opinion or inference on facts or data perceived by or made known to the expert at or before the hearing. As the advisory committee’s notes explain, this sentence allows three sources for the bases of an expert’s opinion: (1) the expert’s firsthand observations of facts or data, (2) evidence presented at trial, and (3) presentation of information or data to the expert outside of the courtroom and other than by the expert’s own perception. Dr. Miller had no contact with Christophersen. He did not testify at trial. Thus, neither source (1) nor source (2) is applicable. Dr. Miller’s testimony falls into the third category.
Rule 703 broadened the ambit of admissible evidence allowed at common law. “The traditional view ... has been that an expert may state an opinion based upon his firsthand knowledge or based upon facts in the record at the time he states his opinion, or based partly on firsthand knowledge and partly on the facts of the record.” E. Cleary, McCormick on Evidence § 14, at 31 (2d ed. 1976). This view barred experts from basing their opinions on facts or data presented to them outside of the courtroom other than such as were gained through the expert’s own perception. The most significant concern underlying this view was hearsay. McCormick states it this way:
A question is improper if it calls for the witness’ opinion on the basis of reports that are not in evidence or are inadmissible as substantive evidence under the hearsay rule (without reciting their contents as hypotheses, to be supported by other evidence as to their truth). The essential objection seems to be that the jury is asked to accept as evidence the witness’ inference, based upon someone’s hearsay assertion of a fact which is, presumably, not supported by any evidence at the trial and which therefore the jury has no basis for finding to be true.
Id., § 15 at 34.
The second sentence of Rule 703 adopted a new approach to trustworthiness. It allows the expert to rely on inadmissible facts or data if they are of a type reasonably relied upon within the expert’s community. See United States v. Williams, 447 F.2d 1285, 1290-91 (5th Cir.1971) (en banc), cert. denied, 405 U.S. 954, 92 S.Ct. 1168, 31 L.Ed.2d 231 (1972). Trustworthiness of facts or data not tested for admissibility is gained through the assurance that the expert’s scientific community reasonably relies on them for the same purpose. See id. at 1290. For example, Rule 703 would permit a doctor to give a diagnostic opinion based upon facts contained in examination or test reports made by hospital technicians even if such reports were inadmissible hearsay, if it is shown that other doctors reasonably rely on such reports when forming similar opinions. Rule 703 says nothing more than that the facts or data need not be admissible in evidence if the reliability inquiry is otherwise satisfied.
*1118If the facts or data are admissible, Rule 703 does not authorize exclusion of the expert opinion. If they are admissible, the inquiry ends, and nothing in Rule 703 authorizes exclusion of the expert’s testimony. If they are not admissible, the district court must determine whether the reliability inquiry is satisfied. If it is satisfied, Rule 703 does not authorize exclusion. If it is not, the district court should exclude the testimony. No other reading is consistent with the plain language, history, and purpose of Rule 703.
Both sentences of Rule 703 apply just to the “facts or data” upon which an expert bases an opinion. Rule 703 does not address “methodology” — how the expert uses the facts or data to form an opinion. Rule 703 does not authorize a court to approve or disapprove the expert’s conclusion. The words of Rule 703 allow use of facts or data “of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject_” The court’s inquiry is not whether experts in the relevant field would reasonably rely on the particular facts or data used by the expert witness. Nor does Rule 703 require a court to determine whether experts in the field would reasonably rely on the same type of facts or data to reach the expert witness’s actual opinion. The rule is met if similar experts use facts or data of the same kind to form opinions on the subject in issue. Cf., Soden v. Freightliner Corp., 714 F.2d 498, 503 (5th Cir.1983).
B. A Wrong Turn Followed.
In Viterbo v. Dow Chem. Co., 826 F.2d 420 (5th Cir.1987), this circuit began disregarding the plain language of Rule 703. Viterbo held that expert opinion testimony may be excluded under Rule 703 if, without regard to the admissibility of the underlying facts or data, other experts in the field would reasonably rely on the facts and data assumed by the expert witness. See id. at 422-24. This interpretation is erroneous for two reasons. First, it disregards the fact that the reliability of the facts and data underlying the expert’s opinion only comes into question if the facts and data are not admissible. Second, it disregards the fact that Rule 703’s reliability inquiry addresses only the “type” of facts and data used by the expert witness and whether experts in the field would reasonably rely on facts or data of that type in forming opinions “upon the subject.” This reliability inquiry provides the only necessary and proper guarantee of trustworthiness.
After Viterbo, our cases continued to follow this erroneous construction. See, e.g., Slaughter v. Southern Talc Co., 919 F.2d 304 (5th Cir.1990); Brown v. Parker-Hannifin Corp., 919 F.2d 308 (5th Cir.1990); Washington v. Armstrong World Indus., Inc., 839 F.2d 1121 (5th Cir.1988) (per curiam); Peteet v. Dow Chem. Co., 868 F.2d 1428 (5th Cir.1989), cert. denied, — U.S. —, 110 S.Ct. 328, 107 L.Ed.2d 318 (1989); Orthopedic & Sports Injury Clinic v. Wang Laboratories, Inc., 922 F.2d 220 (5th Cir.1991).
This en banc court errs when it does not overrule Viterbo and its progeny to the extent that they conflict with Rule 703. We should not follow these cases another step.
After the majority’s footnote 4 states the correct reading of Rule 703, the opinion abandons the concept that the reliability inquiry only applies when the expert’s facts or. data are inadmissible. No mention is made of the admissibility of the facts and data upon which Dr. Miller relied. This is a critical mistake because the facts and data he used should have been considered admissible in evidence.
The majority opinion also approves the district court’s Rule 703 analysis which criticizes Dr. Miller’s facts and data as insufficient support for his conclusion that nickel and cadmium exposure caused Chris-tophersen’s cancer. The Rule 703 analysis is not concerned with whether the facts and data relied on by the expert support the expert’s actual opinion. Even inadmissible facts or data are tested only to determine whether experts in the field would rely on the type of facts or data relied on by Dr. Miller in forming opinions on the subject of cancer causation.
*1119The majority per curiam responds to this latter criticism with illogic. It reasons that giving plain meaning to the words “type” and “upon the subject” “will lead to the irrational result that Rule 703 requires the court to admit an expert’s opinion even if those facts and data upon which the opinion is based are crucially different from the undisputed record.” This stops the process too soon. The fact that Rule 703 does not preclude admissibility does not require that an improperly supported opinion must be admitted. Evidence that passes Rule 703 may be excludable under other rules. For example, the opinion might be irrelevant under Rule 401 or substantially more prejudicial than probative under Rule 403.
The majority says that giving the rule its plain meaning “often will render Rule 703 impotent as a tool for testing the trustworthiness of the facts and data underlying the expert’s opinion in a given trial.” This criticism grafts onto the rule a function that is incompatible with its language and purpose. The trustworthiness aspect of the reliability inquiry has nothing to do with whether the expert’s facts or data provide sufficient support for the expert’s opinion. Rule 703 does not say that the facts or data upon which an expert witness bases an opinion must supply reasonably reliable support for that opinion. Rather, the rule treats the reliability inquiry as a sufficient guarantee that an expert’s inadmissible facts or data are sufficiently trustworthy to overcome the reasons why they are inadmissible. The rules deal with fundamentally unsupported but relevant expert opinions only in terms of probity versus prejudice under Rule 403, discussed below.
C. Rule 703 Applied.
In today’s case, the facts and data upon which Dr. Miller based his opinion were the Manoliu affidavit, Christophersen’s medical records, and medical literature. Judge Reavley’s dissent sets them out in careful, complete, and correct detail. In rendering summary judgment, the district court did not expressly determine that these facts and data could not have been admitted in evidence. For summary judgment purposes, the facts contained in Manoliu’s affidavit should have been considered admissible at trial in the form of Manoliu’s direct testimony. The facts contained in the medical records should have been considered admissible in the form of direct testimony by those who made the records or as records of regularly conducted activity. See Fed.R.Evid. 803(6). Medical records also might be the type of sources of information upon which cancer experts reasonably rely when forming their opinions as to the causes of a person’s cancer. No competent summary judgment proof suggests that they were not. The data contained in the medical literature would have been admissible over a hearsay objection under the learned treatise exception to the hearsay rule. See Fed.R.Evid. 803(18). The majority and the district court did not consider whether the facts and data relied on by Dr. Miller were admissible.
The district court also attempted to determine whether experts in the field of cancer research would have reasonably relied on the particular facts and data used by Dr. Miller (the Manoliu affidavit, medical literature, and medical records) to form his actual opinion (that nickel and cadmium caused Christophersen’s colon cancer). This analysis was also improper. Rule 703 only asks the court to determine whether experts in the field of cancer research would have reasonably relied on facts or data of this “type” in forming opinions or inferences “upon the subject” of cancer causation.
Insistence on a punctilious observance of the intended operation of Rules 702 and 703 does not put form over substance. Rather it enforces the spirit of the Federal Rules of Evidence which provide the trier of fact with all but a narrow band of relevant evidence. Evidence authorized by the literal terms of Rules 702 and 703 may not be excluded unless the court balances probity against substantially greater prejudice as required by Rule 403, discussed below. The majority opinion destroys the value of that weighing because it allows district courts to exclude expert opinions under *1120Rules 702 and 703 for reasons those rules do not permit.
Because the district court’s analysis of Dr. Miller’s testimony was premised on an incorrect legal interpretation of Rule 703 that would deprive a jury of evidence it should be able to consider, I agree with Judge Reavley that exclusion on the basis of Rule 703 was manifestly erroneous and that the majority erred in basing affirmance on this rule.
III. FRYE.
I completely agree with Judge Reavley’s analysis of the limited history of Frye in this circuit and criticism of its adoption here. I support his views with three additional points. First, if Frye is a rule of evidence, it has not survived the enactment of the Federal Rules of Evidence. See 3 J. Weinstein & M. Berger, Weinstein’s Evidence ¶1702[03], at 702-36 (1990); 22 C. Wright & K. Graham, Federal Practice and Procedure § 5169, at 108 (1978). Second, if it is a substantive rule, its adoption in diversity cases is foreclosed by Erie. Until today, this circuit has limited Frye to a narrow class of federal criminal cases to which Erie does not apply. Third, Frye is neither a good rule nor one the Court must adopt to decide this case. Rather than extending Judge Reavley’s critique of Frye, I simply note that the three leading treatises on the law of evidence support my position that Rule 403 is the better test. See E. Cleary, McCormick on Evidence § 204, at 491 (2d ed. 1976); 3 J. Weinstein & M. Berger, Weinstein’s Evidence ¶ 702[03], at 702-34-44 (1990); 22 C. Wright & K. Graham, Federal Practice and Procedure § 5168, at 86-91 (1978).
IV. RULE 403.
In clear declaratory language, Rule 403 grants a limited power to exclude evidence.
Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.
With a footnote, the majority dismisses the pertinence of Rule 403 to today’s case. The district court’s application of Rule 403 is essential to the outcome of the appeal. Individual rules cannot be read in isolation. Rule 403 is as much a part of the Rules of Evidence that govern this case as Rules 702 and 703. If it were not, I would agree with Judge Reavley and join his dissent. However, since it applies as strongly to expert opinion testimony as it does to any other evidence, see 1 J. Weinstein & M. Berger, Weinstein’s Evidence ¶ 403[01], at 403-5 (1989), I would affirm the district court’s decision to rely on it to exclude Dr. Miller’s testimony.
Rule 403 allows a court to exclude relevant evidence when its probative value is substantially outweighed by the danger of unfair prejudice. An expert’s opinion may be based on such erroneous facts or data, such proven unsound methodology, or such internally inconsistent reasoning that its probative value is minimal. I agree with the majority’s footnote 10 which acknowledges that expert testimony may create a special kind of prejudice. When an opinion, especially one a lay person finds as arcane and speculative as cancer causation, is based on erroneous data, reasoning, or methodology, qualifying the opining witness as a medical expert carries a likely danger than the opinion will be substantially more prejudicial than probative. The fact that a witness is labeled an “expert” under Rule 702 would certainly be an improper basis for a jury’s decision to believe the witness’ opinion.
These principles introduce no new concepts into our jurisprudence. While I reject Viterbo’s departure from the plain meaning of Rule 703, I agree with its reasoning that if an opinion is fundamentally unsupported, then it offers no expert assistance to the jury; and that lack of reliable support can render an opinion substantially more prejudicial than probative, making it inadmissible under Rule 403. Viterbo, 826 F.2d at 422; see also Washington v. Armstrong World Indus., Inc., 839 F.2d 1121, 1123-24 (5th Cir.1988) (per curiam).
*1121Judge Reavley’s dissent maintains that, by excluding Dr. Miller’s testimony, the district court took a fact issue from the jury. An analysis of probity versus unfair prejudice almost always depends to some extent on facts, but where undisputed proof supports the district court’s conclusion as it does here, the issue is one properly decided by the court. When a permissible evidentiary ruling, supported by undisputed facts, excludes evidence, it takes away nothing that is proper grist for a jury.
In today’s case, the undisputed record confirms that Dr. Miller relied on erroneous factual assumptions. Dr. Miller formed his opinion and testified at his deposition without any accurate information on Christophersen’s exposure. Dr. Miller admitted that a person’s level of exposure to possible carcinogens is critical. The studies on which he relied indicate that carcinogens exhibit a dose-response effect. Dr. Miller’s only source of information on exposure was Manoliu’s affidavit. Significantly, Manoliu had no idea how much, if any, nickel and cadmium was present in the fumes. Dr. Miller formed his opinion and testified at his deposition without any knowledge of what particles or compounds were present in the fumes or in what concentration, the size of the impregnation and soak rooms where the fumes originated, and the physical structure and ventilation in the plant and Christophersen’s office. Dr. Miller’s only basis for his assumption that the fumes contained any nickel and cadmium at all was Manoliu’s bare assertion that these compounds were present in the fumes because the fumes were irritating. When Dr. Miller was confronted with the fact that he had formed his opinion without any credible exposure data, his sole response was that he would not change his opinion unless it was shown that the fumes contained absolutely no nickel and cadmium. He failed even to attempt to justify this unique view which was at odds with his own view that the level of exposure was critical and contrary to the dose-response effect detailed in the studies on which he relied.
Dr. Miller’s reasoning and methodology were also seriously deficient. He asserted that nickel and cadmium caused Christo-phersen’s small cell colon cancer because they have been associated with small cell cancer of the lung despite the fact that he could cite no authoritative sources for this type of associative reasoning. The uncon-tradicted summary judgment evidence indicated that, without additional support, Dr. Miller’s presumption that nickel and cadmium should be associated with cancerous cells in the colon because they have been associated with a similar type of cancerous cell in the lung is without precedent in cancer epidemiology and has no foundation in medical science. Moreover, Dr. Miller agreed that the determination of the pathogenesis of a particular form of human cancer requires human epidemiological studies, animal studies, arid in vitro testing. He conceded that he had never seen an epidemiological or animal study demonstrating a causal association between exposure to nickel and/or cadmium and colon cancer.1
I do not disagree with the dissent’s view that Dr. Miller’s testimony passed Rules 702 and 703. I very much disagree with its view that the court was required to admit his opinion testimony because the provisions of these two rules were met. The trial court was requested to review the evidence under Rule 403. He did so and concluded that Dr. Miller’s testimony should be excluded.
Under the undisputed portions of the summary judgment record, the trial judge could find that Dr. Miller’s opinion was supported only by his credentials and his persistent refusal to acknowledge the inadequacy of his methodology. The district court determined that the probative value *1122of Dr. Miller’s testimony was substantially outweighed by the danger of unfair prejudice. To reverse this Rule 403 ruling, we must find manifest error. There was none.
V. CONCLUSION.
The majority opinion distorts or ignores the letter and spirit of the Federal Rules of Evidence. Today's case ought to be decided based on the plain language of the three applicable rules. By overlaying these rules with its own agenda for exclusion, the majority disserves our trial judges in this difficult area of their work. The dissent’s refusal to acknowledge that the district court should be trusted to weigh probity against substantial unfair prejudice is equally in error. Because I cannot join either opinion, I respectfully concur only in the affirmance of the appealed judgment.
. Judge Reavley observes that Dr. Miller's contract with Tufts University required him to deliver all consultation fees to the medical school. The suggestion of unbiased objectivity is open to question. The record also indicates that, at the time Christophersen’s lawyer hired him in response to an advertisement in a national legal periodical, Dr. Miller had recently agreed to join the Tufts faculty and was not aware that his new contract would prevent him from continuing to earn money from consulting with lawyers.