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                                                IN THE SUPREME COURT OF THE STATE OF OREGON

                                                          NANCY R. JENNINGS )
                                                                                                  ) Trial Court No. A 9405-03148
                                                                     Plaintiff-Appellant, )
                                                              Respondent on Review ) C.A. No. A92690
                                                                                                  )
                                                                                              v. ) S.C. No.
                                                                                                  )
                         BAXTER HEALTHCARE CORPORATION, )
                                                      a Delaware corporation and )
                                      BAXTER INTERNATIONAL, INC., )
                                                                                                 )
                                                         Defendants-Respondents, )
                                                                                                 )
                                                                                          and   )
                                                                                                 )
                               DOW CORNING CORPORATION and )
                                      WILLAMETTE FALLS HOSPITAL, )
                                                                                                 )
                                                                               Defendants )

BRIEF OF AMICI CURIAE

TABLE OF CONTENTS

Table of Authorities........ ii

Interest of Amici........ 1

Statement of the Case........ 2

Summary of Argument........ 3

Statement of Facts........ 4

ARGUMENT........ 8

I. The discipline of clinical medicine is founded on medical science and the scientific principles are the same as in other areas of science........ 8

II. The Court of Appeals panel was incorrect in its interpretation of the Daubert and the parallel state law principles in Brown and O'Key with respect to reliability of the proffered evidence........ 11

III. The role of epidemiology and toxicology........ 19

CONCLUSION........ 22

TABLE OF AUTHORITIES

OREGON CASES

State v. Brown, 297 Or 404, 687 P.2d 751 (1984)........ passim

State v. Kersting, 50 Or App 461, 623 P. 2d 1095 (1981), aff'd on other grounds, 292 Or 350, 638 P.2d 1145 (1982)........ 12

State v. O'Key, 321 Or 285, 899 P.2d 663 (1995)........ passim

FEDERAL CASES

Daubert  v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed. 2d 469 (1993), on remand 43 F.3d 1311 (9th Cir. 1995), cert. denied ___ U.S. ___, 116 S.Ct. 132 L.Ed.2d 126 (1995)........ passim

Frye v. United States, 293 Fed. 1013 (D.C. Cir. 1923)........ 13, n. 10

General Electric Co. v. Joiner, ___ U.S. ___, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997)........ passim

MISCELLANEOUS

Federal Judicial Center, Reference Manual on Scientific Evidence (1994)........ 10, 20

A.B. Hill, "The Environment and Diseases: Association and Causation," 58 Proc. Royal Soc. Med., Sec. Occup. Med. 295 (1965)......... 20, n.14

K. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge (5th ed. 1989)........ 18, n.12

INTEREST OF AMICI

Amici are scientists who have studied the issue of the role that scientific issues play in public affairs and in particular the way in which they can illuminate disputes between different persons or elements of society in the courts of law. Several of the amici submitted a brief cited with approval by the United States Supreme Court in Daubert  v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) (hereafter "Daubert "), the seminal case discussing the rule for admissibility of expert scientific evidence. Amici support the principles enunciated by the United States Supreme Court in Daubert and by the Oregon Supreme Court in State v. O'Key, 321 Or 285, 899 P.2d 663 (1995) (hereafter "O'Key"); amici believe that those principles are sound, are based on an correct understanding of scientific inquiry, and should have wide applicability at the interface between science and law and policy. Amici were professionally astounded to learn that the three-judge panel of the Court of Appeals in Jennings v. Baxter Healthcare Corporation, 152 Ore. App. 421, ___ P.2d ____ (1998), held in substance that testimony as to medical causation which the physician proffering the testimony conceded is not even a hypothesis, is testimony that is reliable and acceptable under the O'Key standards and Daubert. Amici further believe that the decision of the District Judge Frank L. Bearden to exclude the part of the testimony of Dr. Grimm that dealt with medical causality was well within the scope of the guidelines enunciated by the United States Supreme Court in Daubert and further endorsed and explained by the United States Supreme Court in General Electric Co. v. Joiner, ___ U.S. ___, 118 S.Ct.512, 139 L.Ed.2d 508 (United States Supreme Court, December 15, 1997) (hereafter "Joiner") and by this Court in O'Key. Judge Bearden therefore did not abuse his discretion.

STATEMENT OF THE CASE

The Plaintiff-Appellant in this case is a lady who alleges that she was exposed to silicone from breast implants that leaked and ruptured, causing her personal injuries. The particular claim under discussion is a claim that the exposure to the silicone caused neurological conditions. To establish a causal link between the diagnosis and the exposure to the silicone, plaintiffs proffered the testimony of a clinical physician, Dr. Robert Grimm. The district court admitted a part but not all of Dr. Grimm’s testimony. It excluded the portion dealing with causation under OEC 401 and OEC 702. The jury subsequently rendered a verdict for the defendants. Plaintiffs appealed, and the appeal court reversed and remanded, holding that the district court erred in applying State v. Brown, 297 Or 404, 687 P.2d 751 (1984)(hereafter "Brown") and, implicitly, the Daubert criteria to Dr. Grimm’s proffered testimony as to causation. According to the opinion, Daubert and Brown standards would allow the testimony because it is logically relevant and is "novel" scientific evidence admissible under OEC 702.

SUMMARY OF ARGUMENT

The Court of Appeals panel incorrectly applied Daubert , which has been elaborated upon in Joiner, and which is similar to the procedures of the Oregon courts enunciated in Brown and harmonized with the Federal rules in O'Key.

The opinion of the Court of Appeals is based on a fundamental mischaracterization of Daubert, O'Key and Brown and flawed perception of what constitutes proof of causation in medicine. Daubert itself, and Joiner, which followed, apply the "Daubert factors" to medical science and specifically the issue of causation of disease. The Oregon courts, beginning with Brown, have followed Daubert in all essential respects.

Issues of causation of disease are resolved in medicine using the methodology outlined in Daubert and Brown: formulating an hypothesis, testing the hypothesis, subjecting the hypothesis and the test data to review and testing by others (through publication and peer review), and, if appropriate, refinement, revision or discarding of the hypothesis. The process is not finished when one has data, however reliable, until the hypothesis has been properly stated and tested.

The testimony at issue here and the process by which plaintiff’s expert on causation reached his conclusion do not satisfy the Daubert/Joiner or the Brown/O’Key criteria for reliability, and the trial court properly excluded Dr. Grimm’s testimony on causation. The Court of Appeals did not apply the appropriate criteria, or applied them incorrectly.

STATEMENT OF FACTS

The Petition for Review focuses on the decision of the Court of Appeals reversing the trial court’s rejection of the testimony of Dr. Robert Grimm, an expert called by plaintiff, as it related to "causation" of neurological symptoms. Dr. Robert Grimm, a neurologist, was proffered to testify about medical causation of plaintiff's symptoms. In response to Baxter's challenge to the testimony of Dr. Grimm, the trial court conducted an in limine hearing as directed by O'Key, 321 Or at 307, n. 29. During this hearing, neither plaintiff nor Dr. Grimm presented any independent corroborating testimony or professional literature to support the validity of the methodology and reasoning by which Dr. Grimm reached his opinion, or the validity of the opinion itself. During the in limine hearing, the trial judge questioned the witness to elicit information concerning the factors enumerated in O'Key, and permitted some cross-examination by Baxter's counsel.

Plaintiff "presented" many ailments which are quite common in the population generally: fatigue, aching muscles and joints, sleep disturbance, minor rashes, memory loss, tingling sensation in hands and feet, dizziness, and others. (Tr. 26:15-16, Tr. 26:27) Plaintiff alleged these symptoms were caused by her silicone breast implants. Dr. Grimm was called to testify that tingling in the fingers, sensory loss in the fingers, and balance problems were caused by her exposure to silicone breast implants. Dr. Grimm's opinion that silicone breast implants caused Mrs. Jennings' neurological deficits was based on his study of 50 women, an admittedly biased sample (Tr. 26:40) which led to "very preliminary results." (Tr.27:34)

He acknowledged that his findings had not been peer reviewed or even submitted for peer review, and conceded that more work was required before the results could be published and peer review obtained:

As Dr. Grimm candidly recognized, the question of whether exposure to a substance causes disease is a matter of science for which a particular scientific methodology is employed. (Tr. 28A:35; Tr. 26:38).

In response to questions by the trial court during the in limine hearing, and on cross-examination, Dr. Grimm explained that the scientific method for determining whether a substance causes disease is, first, is carefully to record observations; second, after detailed observations have been made, set up a tentative explanation for the observation, forming an hypothesis; third, conduct tests to challenge ("falsify") the hypothesis to see whether it is true or not (See, e.g.Tr. 26:38, 46).

Dr. Grimm admitted that he had not done any epidemiology or other controlled testing. (Tr. 26:45-46.) His studies on silicone began in the fall of 1993, when he saw two sick women with breast implants. (Tr. 26:7-8). He evaluated 49 women (other than plaintiff) with breast implants to determine if they had neurological signs and symptoms. (Tr. 26:9). On the basis of his observations about neurological signs and symptoms in those 49 patients, and his examination of the plaintiff, he used differential diagnosis to form an opinion that the plaintiff's neurological condition was caused by her breast implants. 152 Or App at 429.

Dr. Grimm asserted that differential diagnosis is a recognized means for deriving a diagnosis. (Tr. 26: 11). He said the conclusions he had drawn "so far [are] based on the best available to [him] differential diagnostic techniques and application of that methodology." (Tr. 27: 34-35).

Dr. Grimm emphasized the "very preliminary" nature of his results. (Tr. 27:34). He acknowledged that he was only at the observation stage; he had not yet even formed an hypothesis; he had no theory of the mechanism by which silicone caused neurological symptoms (Tr. 26:34), he had done no "control testing (Tr. 26:46), and further, his testing of sensory deficits in the women he observed needed to be repeated. (Tr. 28-A:34). Dr. Grimm recognized that his findings of sensory deficits could be tested, but he equivocated about whether his opinion that silicone breast implants caused the neurological deficits could be tested. He candidly admitted that he might be "out in left field" about his opinions (Tr. 28A:36), and that a controlled study could be done:

Dr. Grimm could not identify any other physician who had made similar observations, and acknowledged there is no general acceptance of his causation opinion. (Tr. 26:78-79). Indeed, when the court inquired about the degree of acceptance of his theory or technique, Dr. Grimm responded: "I have no theory at the present time, and I haven't published a thing yet. I'm still in my -- the studies are in progress . . .' (Tr. 26: 33-34).

ARGUMENT

I. The discipline of causation in clinical medicine is founded on medical science and the scientific principles are the same as in other areas of science.

The decision of the Court of Appeals in this case seems to be based on the proposition that causation in medicine can be established by examining an exposed group of patients and making a "differential diagnosis" of those patients, without any comparison to non-exposed "control" sample. This is contrary to our understanding of the evidentiary standards enunciated by the Supreme Court in Daubert   v. Merrell Dow Pharmaceuticals, 126 F.3d 682, and applied to the Oregon state courts by OEC 401 and OEC 702.

In all scientific inquiry, and the study of medicine is no exception, mere observation of an effect is insufficient to justify a conclusion of causation. The Court of Appeals misstated the purpose of differential diagnosis. "A differential diagnosis technique is a systematic approach taught in medical schools and is a generally accepted method of diagnosing the causes of medical conditions. It requires the physician to propose all possible causes of the symptoms and then to rule out as many as possible in order to reach a conclusion about a particular cause." 152 Or App at 426, n 3. Differential diagnosis is in fact a means of choosing among various possible known causes of a disease. It is not a method of determining whether a substance is capable of causing disease at all. There are differences in practice between medical science and "hard science." The effect, condition or disease being studied is often not well and objectively defined. In "hard science" the effect is often very objective and simply defined such as the movement of a galvanometer needle or the lighting of an indicator bulb. In medical science and particularly in the difficult field of neurology, effects are often less well defined. Terms are not always agreed by other medical scientists. It is then more necessary to be careful about ensuring that the "control" group is studied with equal care to the exposed group and preferably by a "blind " study so that one may be sure that biases do not occur due to lack of objectivity. It is necessary to prove that the effect does not exist when the postulated cause is not present.

Dr. Grimm himself provides evidence that his tests are less objective than desirable. In his testimony quoted in the Court of Appeals opinion (152 Or App at 426-427), he points out that the laboratory of Good Samaritan Hospital found that "most of my conduction data was perfectly normal". This should immediately reinforce the need for and importance of blind controls -- yet none are mentioned. Referring to the patients he had seen, he claims a "unique pattern." Yet he has not described how his patients were referred to him, and one is left to speculate on the likelihood that they may have been preselected for unusual symptoms -- in which case any ordinary statistical analysis would be invalid. The control population implied in the word "unique" is not mentioned and may not exist. The words "there's unquestionably a very strong correlation" sound hollow in this context. There was no control group (Tr. 26:46, see also 152 Or App at 427). The Court of Appeals exaggerates in saying that Dr. Grimm's "hypothesis" "is based. . . on scientific methodology." Such methodology as was described does not fit the definition of scientific accepted by the amici.

The opinion of the Court of Appeals makes frequent reference to the "differential diagnosis" technique. Differential diagnosis is indeed taught in medical schools. But it is not a technique that can be used by itself to prove causation. Used by itself, differential diagnosis can only be used to generate hypotheses. Used in conjunction with other data showing a genuine statistically reliable correlation exists it can be used to assign causation in a specific case. After a hypothesis has been generated an epidemiological study, with proper control groups, can be performed in an effort to prove causation. To suggest that a differential diagnosis can be used by itself as reliable evidence of causation is a view of medicine that is now outdated, if ever it had any acceptance. The fact that more scientific approaches to medical causation are now an integral part of science can be demonstrated by reference to the Encyclopedia Britannica at 774 (15th ed., 1994)(hereafter "Britannica"):

The Reference Manual on Scientific Evidence of the Federal Judicial Center (1994)(hereafter the "Reference Manual") treats medical expert testimony as a part of "science" testimony. The Reference Manual is replete with references to medical testimony as one of those types of expert testimony which are to be treated as "scientific" evidence. Indeed, the Reference Manual contains two lengthy and detailed "reference guides" on Epidemiology (Reference Manual at 121-180) and on Toxicology (Reference Manual at 181-220). Although amici recognize that the Reference Manual is not binding in federal court, let alone in the courts of the State of Oregon, we submit that it is a sophisticated, instructive and useful guide for all judicial proceedings in forums whose rules of evidence are similar to the Federal Rules of Evidence.

In addition to a failure to understand what constitutes reliable evidence of medical causation, the Court of Appeals panel has a crabbed understanding of what constitutes general acceptance in the field. The Court of Appeals quoted with approval the testimony of Dr. Silverman (who was allowed to testify for the plaintiffs over the objections of defendants) which refers to a series of articles by an "ad hoc" group "Silicone Related Disorder Study Group" who have done evaluations solely for plaintiffs in breast implant cases. This group has not published its scientific studies in peer reviewed journals that we are aware of. Moreover the Court of Appeals explicitly refers (152 Or App at 436-437) to Dr. Silverman's testimony about a "Delphic" panel convened by this group. Delphic studies are sometimes performed in the scientific world, but are not very often accepted. It is crucial in such a study to be sure that a range of expertise and opinion is represented. To state, as the Court of Appeals does that "the panel's findings corroborate Silverman's opinions" without any inquiry about the composition and breadth of the panel, the possible conflicts of interest and possible biases of such a panel is, in the opinion of amici completely inappropriate.

II. The Court of Appeals panel was incorrect in interpreting the application of the Daubert  principles and the parallel State principles in Brown and O'Key with respect to reliability of the proffered evidence.

The clinical practice of medicine involves the application of scientific knowledge and is subject to the same evidentiary standards as any other testimony relating to science or the application of scientific principles or data. This conclusion was clearly the basis of two Supreme Court opinions: In Daubert the Court emphasized that a trial judge "must ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable" (509 U.S. at 589), going on to state that "reliability" in this context means not only consistency of results but also what scientists term "validity" or correspondence to reality (509 U.S. at 590, n 9). In Joiner, the Court emphasized the importance of reliability. In assessing reliability there are a number of factors to be considered. One factor stated in Daubert is whether the work has been subjected to peer review or otherwise been open to discussion and criticism outside the strict bounds of this case. As stated by Dr. Grimm the work has not been and in its present form will not be (Tr. 26:34). This factor is also implied in the six rules identified in Brown.

In O'Key, this Court identified the Daubert decision as "an appropriate further development of the decisional process that we first discussed in Brown and Milbradt" (321 Or 285). In State v. Milbradt, this Court admonished litigants that the [Brown] factors are "the necessary foundation that must be laid for the introduction of scientific evidence."

In Brown, an opinion written by Justice Robert E. Jones, this Court disavowed the prevailing "general acceptance" test for admissibility of scientific evidence and adopted a new test of scientific validity for trial courts "[t]o determine the relevance or probative value of proffered scientific evidence." Brown, 297 Or at 417. In Brown the court decided "the standard to be used in determining the admissibility of novel scientific evidence." 297 Or at 408 (quoting commentary to OEC 702). The court adopted "traditional admissibility standards for expert testimony," 297 Or at 408 and "strengthened by consideration of certain factors," 297 Or at 416. In doing so, the Brown court rejected both the general acceptance test, and the "reasonable reliability" alternative proposed by the Court of Appeals in State v. Kersting, 50 Or App 461, 623 P. 2d 1095 (1981), aff'd on other grounds, 292 Or 350, 638 P.2d 1145 (1982).

The Court of Appeals itself (152 Or App at 429) conceded that Dr. Grimm merely has an hypothesis (and Dr. Grimm testified that it was not yet even an hypothesis). The issue then arises whether the alleged "hypothesis" is so compelling that it should be considered by non-experts as a guide to their actions, in this case to assign blame for an injury? It is precisely this role the trial court must perform as "gatekeeper." If Dr. Grimm himself thought his idea was "novel" but valid, surely he would have spread his information more widely. He himself says that what he observed is a "condition" not a "disease."(Tr.26:62) He questioned the reliability of his tentative theory more emphatically when he stated "Yes, I could be terribly wrong. That's quite true. But not wrong in my observations. The question is -- As I say I haven't got to a hypothesis stage." (emphasis supplied)(Tr. 28A:36)

It seems strange to the amici that a scientist should be willing to ask the jury to act upon the basis of ideas which he has explicitly stated he is not yet ready to discuss with his peers. It seems to the amici that it is just this kind of proffered testimony that the United States Supreme Court wished to exclude in Daubert and Joiner. The appeal court failed to observe the similarity with respect to the type of expert evidence offered, but rejected, in the two cases decided by the United States Supreme Court -- Daubert and Joiner.

Both Daubert and Joiner were cases involving medical science and the causation of the plaintiff’s condition; in both cases the issue on appeal was the correctness of rejection by the trial court of proffered testimony as to causation. In Daubert the issue was whether the deformities of plaintiffs’ child were caused by the alleged mutagenic effects on fetuses of the drug Bendectin taken by their mothers during pregnancy. In Joiner the issue was whether the plaintiff's exposure to fumes from polychlorinated biphenyls (PCBs) caused or contributed to his small cell lung carcinoma. In both Daubert and Joiner, the proffered evidence that was excluded was testimony as to claimed evidence of causation. The plaintiffs in Daubert claimed that various problems that appeared in pregnancy and childbirth were due to use of the drug Bendectin. The Supreme Court, declining to adopt the "Frye rule," set forth a number of criteria for determining the scientific validity of proffered testimony:

Daubert , 509 U.S. at 593-594.

The answers to the above principles when applied to Dr. Grimm's proffered testimony, seem to be:

      Similar factors were listed in Brown, 297 Or at 417:

        1. The technique's general acceptance in the field

        2. The expert's qualifications and stature

        3. The use which has been made of the technique

        4. The potential rate of error

        5. The existence of specialized literature

        6. The novelty of the invention

        7. The extent to which the technique relies on the subjective interpretation of the expert.

Applying these criteria, we submit that the correct analysis is:

(1) The technique has had no chance to be accepted or rejected.

(2) Amici have no reason to doubt Dr. Grimm's credentials as a neurologist, but have insufficient information as to his experience as an epidemiologist or toxicologist.

(3) Since no proper control group is present the use of Dr. Grimm's data is not proper.

(4) See (3) above.

(5) Although the physiological and biochemical effects of silicone have been studied in depth in numerous epidemiological studies, there is no specialized literature on the neurological effects of silicone. This suggests that Dr. Grimm's postulated link between silicone and neurological deficits has not been observed by other scientists.

(6) The idea is novel in the sense that no one else seems to have heard about it. But see our comments on "novelty" below.

(7) The technique relies almost entirely on the subjective interpretation of the expert. Dr. Grimm explicitly mentioned that when he checked "most of the conduction data were perfectly normal." (152 Or App at 427)

When Daubert was remanded to the Court of Appeals for the Ninth Circuit (because that court had applied the "Frye rule" in the proceedings that led up to the Supreme Court’s decision), that court, on applying the Supreme Court’s standards, concluded that evidence to the effect that Bendectin "causes" the alleged medical problems was correctly excluded under the Daubert guidelines. Daubert  v. Merrell Dow Pharmaceuticals, 43 F.3d 1311 (9th Cir. 1995), cert. denied ___ U.S. ___, 116 S.Ct. 189, 132 L.Ed.2d 126 (1995).

In Joiner, recently decided by the Supreme Court, the issue was whether the claimed exposure to PCBs was a cause of the admitted disease. Joiner also was a case which, like this case, is about causation. In Joiner proffered expert testimony by two physicians was excluded by the trial court and the Supreme Court, reversing the Court of Appeals for the Eleventh Circuit, agreed that it was correctly excluded because it was not "reliable." In both of those cases, the experts for the plaintiffs had not shown that their research or their review of the literature was applicable to the issue of causation in humans of the disease contracted by the plaintiff.

Indeed, in Joiner the unanimous court went further than did the majority in Daubert , and actually examined not only the methods, but also the conclusions, of the proposed experts. In Joiner respondent argued that under Daubert the "focus, of course, must be solely on principles and methodology, not on the conclusions that they generate." 509 U.S. at 595, and that because the District Court's disagreement was with the conclusion that plaintiff’s experts

drew from the studies, the District Court committed legal error and was properly reversed by the Court of Appeals. The Supreme Court held, however, that

___ U.S. ___ , 118 S.Ct. 512 at 519.

It appears to amici that this paragraph applies directly to the trial court's refusal to permit Dr. Grimm's opinion to be submitted to the jury in this case

The United States Supreme Court in Joiner held that it was within the District Court's discretion to conclude that the studies upon which the experts relied were not sufficient, whether individually or in combination, to support their conclusions that Joiner's exposure to PCBs contributed to his cancer and that the District Court did not abuse its discretion in excluding their testimony. Id. at 519.

We respectfully submit that the Court of Appeals erred in considering that Dr. Grimm's proffered testimony would do anything but confuse the jury. Non-scientists tend to be confused by untested hypotheses and that is a reason why they are excluded by the Daubert criteria.

Dr. Grimm's proffered conclusion as to causation was not even, by his own admission, a hypothesis that could be tested, it had not been tested, the underlying data and the hypothesis had not been submitted for peer review. In short, there has been no opportunity to falsify Dr. Grimm’s embryonic hypothesis.

The necessary attribute of any scientific theory, including a medical theory of causation, is "falsifiability," that is, whether it can be tested. This was emphasized by Sir Karl Popper, a philosopher of science quoted by the Supreme Court in Daubert (509 U.S. at 593). If a scientist, whether physical scientist or physician, has a theory, it is useful only if it is falsifiable or testable; this is an important mechanism for permitting others to try to "falsify" one scientist’s hypotheses is by publication and peer review. A few scientific facts that Dr. Grimm has not yet wanted to share with his peers to help generate a scientific hypothesis should not be introduced as evidence for causation.

As such, his conclusion that silicone breast implants caused plaintiff’s symptoms did not comport with the requirements of science properly conducted and correctly understood. Amici submit that the trial court judge correctly excluded Dr. Grimm's unreliable testimony.

III. The role of epidemiology and toxicology.

One of the erroneous ideas that is implied in the opinion of the Court of Appeals is that all physicians are expert in assigning causation and also that assigning causation is the prerogative of the medical profession (i.e., persons who hold the "Doctor of Medicine" or "M.D." degree or its equivalent). There are of course many ways of subdividing the large field that is modern medicine. Here we subdivide it into three roughly separable parts: Diagnosis, Treatment, and Assignment of Causation. An expert in one may not be an expert in another. The usual role in which the lay public (including by this term scientists in other disciplines and lawyers) see a medical practitioner is in the first two of these: diagnosis in an individual patient of a disease and treatment thereof. In the case under discussion, the issue is not whether a witness is an expert in diagnosis and treatment. The issue is whether he is expert in, and proffers reliable testimony in, the field of assignment of causation. Individuals with degrees in biology, chemistry, epidemiology, pharmacology, physiology, toxicology and many other disciplines in addition to medicine can and do conduct relevant research and form viable hypotheses about the causation of disease in this context.

One of the main ways of determining causation is to study a group of people with the same condition or disease, and endeavor to discover a common link between them that might explain the condition or disease. This is the field called epidemiology. The first step is to find a well established statistical "association" between the disease and the cause. This must be free of statistical error. If there is a possible bias in selection of patients, or an inconsistent comparison of patients and controls, the association may be statistically invalid. In all of these (bias in patient selection, absence of proper control) the interpretation of Dr. Grimm's observations may be incorrect. But it is not even enough that there be a statistical association between the hypothesized cause and the disease. There are well defined scientific principles that are used to evaluate whether a statistical "association" that is found should be considered to be "causal." In epidemiological terminology, if the relative risk, or "Risk Ratio," was very large, there is a greater likelihood that a particular exposure causes a particular disease. See Reference Manual at 147-148.

It would be inappropriate for a court to allow the introduction of "scientific" evidence on medical causation without evidence also being proffered on the principles themselves, the logic behind them, and the degree to which the proffered testimony satisfies the criteria of epidemiology with regard to causation. Dr. Grimm was not proposing anything close to this logical argument.

Even if it is accepted that a particular agent or mixture of agents can cause a particular disease, it does not follow that the inverse is true: that the particular disease is always caused by that particular agent. (In this case, even if breast implants were known to be sometimes a cause of neurological symptoms, it would not necessarily follow that observation of these symptoms implies that they were caused by breast implants. In deciding upon causation, therefore, it is necessary to consider the relative roles of all possible causes of the disease in question, even if some of those causes are unknown. This procedure can be bypassed logically only if there is evidence that the only possible cause of the disease is the one being considered, and no cases of the disease have ever appeared in the absence of this specific cause. That is manifestly not the case with the neurological conditions observed by Dr. Grimm -- inner ear dysfunction and loss of sensation in the extremities.

In the absence of such evidence of specificity, it is well accepted that some estimate of the relative probabilities must be made. The probability of Causation can be related to the risk of an individual getting the disease from a given dose by the formula:

Probability of Causation = (Risk calculated from exposure to the particular agent)  / (Risk calculated from all causes)

When the risk calculated from the exposure to a particular agent is greater than the risk from exposure to all causes, which happens when the risk ratio is greater than two. For example, the probability that a particular lung cancer was caused by cigarette smoking can be has high as 90% for heavy smokers, with a risk ratio of 10 or 20. As amici understand the record in this case, no such evidence was proffered by Dr. Grimm and therefore the trial judge did not abuse his discretion in excluding his testimony as to causation.

CONCLUSION

For the foregoing reasons, amici respectfully submit that this Court should grant the petition for review and reverse the decision of the Court of Appeals.

Dated: May 6, 1998

Respectfully submitted,

_________________________________

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