Case Title: Jennings v. Baxter Healthcare Corp.

Citation: 

Docket Number: S45239

State: oregon

Court: Oregon Supreme Court

Date: 2000-11-17T00:00:00Z

Document:
Filed:  November 17, 2000
IN THE SUPREME COURT OF THE STATE OF OREGON

NANCY R. JENNINGS,
	Respondent on Review,
	v.
BAXTER HEALTHCARE CORPORATION,
a Delaware corporation, and BAXTER
INTERNATIONAL INC., a Delaware corporation,
	Petitioners on Review,
	and
DOW CORNING CORPORATION, and
WILLAMETTE FALLS HOSPITAL,
	Defendants.
(CC A 9405-03148; CA A92690; SC S45239)

	En Banc
	On review from the Court of Appeals.*
	Argued and submitted January 12, 1999.
	Jonathan M. Hoffman, of Martin, Bischoff, Templeton,
Langslet & Hoffman LLP, Portland, argued the cause and filed the
briefs for petitioners on review.  
	Linda K. Eyerman, of Gaylord & Eyerman, P.C., Portland,
argued the cause and filed the briefs for respondent on review.
	David B. Smith, Tigard, and Martin S. Kaufman, of Atlantic
Legal Foundation, New York, filed briefs on behalf of amici
curiae Robert K. Adair, Bruce N. Ames, Patricia A. Buffler,
Michael Gough, Joshua Lederberg, Rodney Nicholas, Robert Nolan,
Dimitrios Trichopoulos, M.D., Arthur Canfield Upton, James D.
Watson, James D. Wilson, and Richard Wilson.
	Paul A. Cooney, of Cooney & Crew, P.C., Portland, filed a
brief on behalf of amicus curiae Oregon Medical Association.
	Roy Pulvers, of Lindsay, Hart, Neil & Weigler, LLP,
Portland, filed a brief on behalf of amicus curiae Oregon
Association of Defense Counsel.
	R. Daniel Lindahl, of Bullivant, Houser, Bailey, Portland,
filed a brief on behalf of amici curiae Defense Research
Institute and International Association of Defense Counsel.
	William B. Crow, of Miller, Nash, Weiner, Hager & Carlsen
LLP, Portland, filed a brief on behalf of amicus curiae Product
Liability Advisory Council, Inc.
	David F. Sugerman, of Paul & Sugerman, PC, Portland, and
J.P. Toby Graff, of Graff & O'Neill, Portland, filed a brief on
behalf of amicus curiae Oregon Trial Lawyers' Association.
	VAN HOOMISSEN, J.
	The decision of the Court of Appeals is affirmed.  The
judgment of the circuit court is reversed, and the case is
remanded to the circuit court for further proceedings.
	*Appeal from Multnomah County Circuit Court,
	 Frank L. Bearden, Judge.
	 152 Or App 421, 954 P2d 829 (1998).
		In this product liability action, plaintiff appeals
from a defense verdict.  She alleges that she was exposed to
silicone from breast implants that leaked and ruptured, causing
her personal injuries.  The Court of Appeals reversed and
remanded for a new trial, holding that the trial court committed
reversible error in excluding certain opinion testimony of
plaintiff's expert witness.  Jennings v. Baxter Healthcare Corp.,
152 Or App 421, 954 P2d 829 (1998).  Defendants seek reversal of
the Court of Appeals' decision and reinstatement of the trial
court's judgment.  For the reasons that follow, we affirm the
decision of the Court of Appeals.
I.  FACTS

		In 1978, plaintiff received silicone gel breast
implants following a bilateral mastectomy. (1)  Both implants
partially deflated:  the first in 1980 (which was replaced), the
second in 1992.  In 1993, plaintiff had the implants surgically
removed, at which time it was discovered that one implant had 
ruptured.  Plaintiff filed this action in 1994, alleging that
silicone from the implants had migrated throughout her body and
caused personal injuries.  Defendants maintained that plaintiff's 
symptoms were caused by fibromyalgia and were not the result of
the breast implants. (2)
		At trial, plaintiff called Dr. Grimm to testify about
medical causation.  Grimm is a board-certified neurologist with
an advanced degree in neurophysiology. (3)  Defendants did not
question Grimm's qualifications to determine the causes of
neurological deficits in patients in general, but did challenge
Grimm's opinion testimony regarding causation in this case.  In
response to defendants' admissibility challenge, the trial court
conducted an in limine hearing as directed by State v. O'Key, 321
Or 285, 307 n 29, 899 P2d 663 (1995). (4) 
		At the hearing, Grimm testified that he became
interested in the neurological consequences of silicone in 1993,
when he examined "two very sick women."  As a result, he began to
examine women who had silicone breast implants.  At the time of
plaintiff's trial, he had examined about 50 women, 45 of them in
1994.
		Grimm testified that, among the women he had examined,
he found
	"a unique pattern that I had never seen in any other
neurologic disease in this sample of women.  Basically
two features.  One was that they were all relying on
vision for their balance, because there was something
wrong with their inner ear in the absence of the usual
things of trauma, concussions, tumors, infections,
genetic histories, et cetera.      
		"And the second thing was that while all of them
had -- I can't say all, but we'll say 95 percent -- had
patterns and complaints of tingling in their fingers
and so forth, most of them were unaware that there was
a loss of sensation, actual physical loss of sensation
to touch, in their fingers and toes." 
Grimm found that 43 of the 45 women he had examined in 1994 had
vestibular difficulties: (5)
	"I had never seen in my career widespread neurologic
disorders, or read about as a neurologist this -- what
I thought was a unique pattern.  When 45 women come in,
they're sent to me from different places, and they have
different implant stories, different health histories,
different physical troubles, past histories, and so
forth.  And the unique thing was that there was an
extraordinarily high correlation, 95 percent had the
combination of unusual sensory patterns and the inner
ear."  
(Emphasis added.)  Grimm further testified that the pattern he
had observed in the women was distinguishable from a cross
section of the population at large.  He indicated that the
combination of the two conditions is extremely rare, even among
people with neurological disorders.  Grimm acknowledged that his
findings had not been published in any medical literature or
subjected to peer review.
		Grimm examined the women in his study as follows:  
First, he performed "a classic neurologic examination."  That is,
he mapped the areas where the patient had lost sensation using 
	"pins and brushes, with [the patients'] eyes closed,
going back and forth and making marks on their skin, in
exactly what areas of hands or a foot * * * where the
reception was down.  And I would do this in various
ways to test the veracity of the patients."
Second, he sent the patients to the vestibular laboratory at Good
Samaritan Hospital in Portland.  That laboratory measured each
woman's inner ear function.  With some of the women, Grimm had
additional tests performed.  
		In an attempt to determine the cause of the women's
symptoms, Grimm then performed a differential diagnosis. (6)  In a
differential diagnosis, a doctor develops a list of all diseases
that might cause a patient's symptoms and then, by a process of
elimination, narrows the list.  Mary Sue Henifin, Howard M.
Kipen, and Susan R. Poulter, Reference Guide on Medical
Testimony, 463, in Federal Judicial Center, Reference Manual on
Scientific Evidence (2d ed 2000) (hereinafter Reference Guide on
Medical Testimony).  Grimm also examined the women's histories
and possible exposures for other causes of the same symptoms. 
Silicone was the only common exposure he found among the women. 
Grimm also considered the research of others on animals.
		Respecting Grimm's ultimate conclusions about medical
causation, plaintiff's counsel asked:
		"* * * [H]ave you limited your involvement and
workup and conclusions that you would express today to
your field of expertise -- that is, to say,
neurology -- and drawing conclusions about the
relationship between silicone exposure and the
neurological ramifications of these women's health?
		"A.  Yes."
		Plaintiff's counsel then introduced the subject that
lies at the heart of this case, viz., Grimm's opinion as to the
cause of plaintiff's condition:	
		"Q.  And have you formed an opinion to a
reasonable medical probability based on established and
accepted medical and scientific methodologies that
silicone has caused a condition in these women?
		"A.  Yes.  I think there's unquestionably a very
strong correlation.  What I don't understand is the
mechanism yet.  That, I'm working on.  I cannot say
that I have got to that point in my work, that I
understand the mechanism.  It's unquestionable about
the association in these patients with their unusual
neurological picture.
		"Q.  Are you in a position, then, based on your
work and the application of scientific methodology, to
express opinions based to a reasonable scientific
probability, one, that a silicone-related neurological
condition exists?
		"A.  Yes.
		"Q.  And, two, based on your evaluation of
[plaintiff], she has the signs and symptoms of such a
condition?
		"A.  Oh, yes.  Easily."
(Emphasis added.)  It appears that plaintiff's counsel intended
the foregoing exchange to be -- and that the trial judge and
defendants accepted it as -- a statement that, in Grimm's
opinion, plaintiff's condition was caused by the ruptured
silicone gel breast implants.
		The trial judge then examined Grimm.  The judge
apparently had understood Grimm to have testified that the
conditions he had observed in the women were not proved by any
scientific study.  Grimm clarified that point:
		"Oh, we have elegant proof of the involvement of
the eighth nerve, which is the inner ear, and I'm doing
the science right now.  I haven't published it yet,
because I'm waiting to take a two-year look at this
whole problem.
		"You couldn't ask for better -- for better proof
or better science at the present time with respect to
inner ear function.
		"What I don't understand yet is the mechanism for
the other half of the equation, is the sensation."
		The judge asked Grimm whether his technique could be
"tested."  Specifically, the judge asked whether Grimm had used a
questionnaire because, "if [you] have a questionnaire, they can
look at that and see if you asked the right questions and what
answers you got."  Grimm responded that he had not used a
questionnaire, but that he had used the "classic technique" of
"taking a careful clinical history."
		The judge asked Grimm whether he had submitted his
notes and documentation for peer review.  Grimm responded that 
	"[t]hese are studies in progress.  I have not submitted
this for publication, at which time a very -- as you
can understand, a critical review goes with a jury of
my peers, on whether or not I have followed this very
first rule of all clinical examinations." 
		The judge asked Grimm whether his technique had a known
or potential rate of error.  Grimm responded that the potential
error rate appeared to be about five to seven and one-half
percent.  According to Grimm, the laboratory data on balance was
"the best data in the world on measurement error in this
business."  
		The judge asked Grimm about "the degree of acceptance
in the relevant scientific community, widespread acceptance of
your particular theory or technique."  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.  And I haven't -- I presented
this at a science fair from my own institution, which
is sort of an annual program for work in progress, but
I have not yet presented this data yet, because it's
not complete, to any scientific meeting."
		The judge then asked Grimm about his sample group. 
Grimm noted that most of the 45 women he had examined had been
referred to him by rheumatologists and immunologists who
suspected neurological problems.  About 25 percent were referred
to him by attorneys.  Grimm stated:  "They were sent to me very
specifically.  It's a very biased sample of people."
		The judge asked Grimm how he knew that the women were
distinct from a cross section of the general population.  Grimm
responded that, in his practice, he had examined "maybe 10,000
individuals for neurologic diseases."  He added that he sees only
patients "who complain if something is going wrong with their
machinery, in terms of balance or vision or whatever, that has to
do with the nervous system."  Generally, his patients have severe
problems; general practitioners see patients with lesser
problems.
		Finally, the judge questioned Grimm about his use of
the word "condition," rather than the word "disease."  Grimm
explained:
		"I think it's probably best to err on the
conservative side of things.  In the first stages of
any observations, the first stage of science, is just
to write down what you see and what you hear and what
the evidence is, make as careful observations as you
can and leave off the words that sort of prejudge, like
a 'disease.'  If somebody has been intoxicated with
somebody [sic] and has a set of neurologic symptoms and
you take the thing that's intoxicating them and it gets
better, you might not call it a disease but a disorder,
dysfunction, or something like that.  And I try to not
use the emotional labels on it.  A lot of those labels
will prejudge a situation." 
		Plaintiff's counsel then examined Grimm:
		"Q.  * * * [t]he methodology that you've employed
in addressing questions for these 50 or so women, is
all of that work based on generally accepted scientific
principles and medical principles?
		"A.  I believe so, yes.
		"Q.  Is all of your examination technique based on
standard neurological examination technique?
		"A.  Yes.
		"Q.  Is all of your sorting out and correlating
and identifying of patterns and ruling out of other
explanations based on standard medical and scientific
principles?
		"A.  Yes.
		"Q.  So with respect to the route you've taken and
the means you've used to get to your conclusions, you
have no trouble saying that that is all based on
accepted theory and technique?
		"A.  No."
		After extensive discussion with counsel, the trial
judge announced his ruling:
		"I don't have a problem with [plaintiff's] theory
that [State v. O'Key, 321 Or 285, 899 P2d 663 (1995)]
doesn't apply to medical doctors who are coming in and
giving a diagnosis based on their specialty.
		"To the extent, however, that the diagnosis
involves a new but unproven theory -- proven, that is,
by the O'Key methods -- not necessarily because the
doctor says.  It's proven to him -- O'Key says let's
check it out.  Has there been peer review?  Has there
been a methodology compared to samples?  Has there been
an error study done, so we know at least there's a
possibility of error?  Just seeing the 43 out of 45
doesn't mean that it's an absolutely perfect
study. * * *
		"[Grimm] can obviously say what he saw, and he can
say that he's noticed a strong correlation between what
he saw with [plaintiff] and what he has seen with some
of his patients who have had silicone implants,
multiple implants, and to that point I'm not seeing a
serious problem.
		"As soon as he takes it a step further and it
looks like to the jury that there is a disease out
there called silicone-related disorder and she has it,
I'm a little bit concerned, because I don't see the
O'Key test met, particularly when the doctor talks in
terms of correlation.  When he says it's a condition,
not a disease, and you are asking him causation and
he's explained to me why it's a condition at this
point, because he doesn't want to use the word
'disease' until he's further on in the studies -- "
(Emphasis added.)  At that point, counsel interrupted the judge
and the judge did not complete his thought.
		The judge then continued:
		"[Grimm] can testify to his observations of
symptoms in [plaintiff].  He did examine her.  I'll
certainly take his word that he did a history; that he
does, in his clinical practice that is an accepted
method, a thorough history, did it orally without using
a questionnaire, but I have no reason to doubt his
ability to do it or his statement that it's a history
that is well-accepted within certainly the neurological
community.
		"But he said he finds -- once he checked those
symptoms out and because he's seen similar symptoms in
45 of his 10,000 patients, he sees a pattern, and the
last women he saw have had silicone implants.  He sees
the correlation, a strong correlation between those two
symptoms, the pattern of those two symptoms and women
who have had -- or at least the 45 women who have had
breast implants.
		"But that's as far as I think he can go.  To say
that it's a cause of a disease that's undefined --
well, it isn't even a disease.  Dr. Grimm can't say
it's a disease -- and he doesn't yet understand the
mechanism.  Someday he will, but he doesn't yet
understand the mechanism.  I just don't think he can go
any further than that."
(Emphasis added.)
		Plaintiff's counsel asked the judge whether Grimm could
opine that, more probably than not, plaintiff's two symptoms were
caused by silicone.  The judge answered:
		"No, I don't think he can say that.  I think he
can say -- I think he can say what he did say.  He did
say in his diagnosis that there appears to be a strong
correlation between women who have had silicone
implants -- at least these last few women he's look[ed]
at -- women who have had silicone implants, there's a
strong correlation, and these two symptoms, and he
doesn't understand the mechanism of it, but between
these symptoms, he's qualified to say that.  That's
what he did say.  I don't have a problem with that.
		"But to stretch him and make it a causal -- use
that word, 'There is such a thing as silicone-related
disorder.  I've examined [plaintiff] and she has
silicone-related disorder based on my evaluations' -- I
don't think he needs to go through the O'Key test as a
medical doctor, but when he takes that one extra step
and says, 'What I observed in the symptoms belongs to
this category,' when he says, 'So far it's not a
disease,' and so far he's still checking out things
like error, peer review, things like that that still
haven't happened, I think it would be inappropriate."
(Emphasis added.)
		Plaintiff's counsel continued:  
		"I think what Dr. Grimm can do, and maybe we
didn't really get to this point clearly, you know, he
can say, 'I see this correlation,' but then -- if in
terms of what will -- then 'Do you think that silicone
is causing [plaintiff's] case,' he would say that 'I
put 25 or 30 possible causes on my differential, and I
have systematically ruled them out and the only one
that's left is silicone exposure.'  And that, of
course, makes it consistent with -- I mean, the
correlation, then gives me the support.  So there's
actually two factors."
The judge responded:
		"As long as we don't get to the point that anyone
mentions the word 90 or 95 percent type of thing,
because that's only with these 45 women.  It's not with
all of the patients he has seen who have had whatever. 
I don't want the jury to believe that somehow this is a
magic number, because I'm pretty certain it isn't.
		"* * * * *
		"At some point I don't mind getting the fact in
front of the jury that I just mentioned, that small-level fact, and they can draw whatever inferences you
argue to them or what they draw on their own.
		"What I don't want to have happened is placed for
them as a fact, by way of opinion, that based on the
preliminary methods and the preliminary work that Dr.
Grimm has done so far, he's in it for the Nobel Prize,
and discovered a new disease and she has it.
		"There may come someday where there are
established epidemiological studies and enough experts
that can tie this and somebody can say it's a cause. 
I'm just a little concerned -- I mean, if you say, to a
reasonable medical probability or scientific 
probability, is there a correlation between what you
observed in [plaintiff] and a response to silicone, or
something of that nature, I think I could be
comfortable with that.  A correlation is what he said. 
You can still use the reasonable medical probability if
he's talking as a doctor doctor, and I think he is,
because if we say scientifically probable, we trigger
O'Key."
(Emphasis added.)
		Plaintiff's counsel continued:  
		"[Grimm] is here, first and foremost, as a medical
doctor."
The judge responded:  
		"Okay.  So if you say, 'Doctor, to a reasonable
medical probability, the symptoms that you have
diagnosed in [plaintiff], you say to a reasonable
medical probability there's a strong correlation
between those symptoms and silicone' -- now, I may
revise that in * * * a minute, but that sounds like
something that I could deal with.  He's not using the
word 'cause,' he's not say[ing] 'the studies show' and
he's not saying silicone-related disorders, but you
said silicone exposure -- there's a strong correlation
between the symptoms he's found and exposure to
silicone, now that I think he can say, and I
think * * * it will stand the test.
		"But if you get too much further out of that, I'm
going to be real concerned, because I do see somewhere
a bright line where we get beyond his medical diagnosis
into where he's given a scientific opinion as to the
fact of silicone-related disorder and a direct
causation of that disorder when we're so preliminary at
this point."
(Emphasis added.)
		Plaintiff's counsel then asked:
		"What you're saying is he can say more probably
than not there's a correlation, but he can't say more
probably than not this is the cause --
		"THE COURT:  Yeah.  I think I could --
		"[Plaintiff's Counsel]:  -- to a reasonable
medical probability?
		"THE COURT:  -- to a reasonable medical
probability.  And I would let you lead on that point so
that we don't go jumping around."
		In response to a request by defense counsel for cross-examination, the trial judge stated, in part:  
	"[W]e've got a potential of an opinion crossing a
discipline from medical into more or less a scientific
certainty.  I think we're stopping short of that, and I
think it's all right." 
		As noted, the jury returned a verdict for defendants,
and the trial court entered judgment accordingly.  Plaintiff
appealed, assigning as error, inter alia, the trial court's
ruling excluding Grimm's causation testimony. 
		The Court of Appeals reviewed the trial court's ruling
as a matter of law and concluded that the trial court erred when
it excluded Grimm's opinion testimony about causation.  Jennings,
152 Or App at 429.  The court explained:
	"Whether Grimm's hypothesis is correct was a question
of fact for the jury to decide in connection with the
other evidence on the issue.  In sum, we hold that
Grimm's opinions meet the threshold requirement of
logical relevance and that [defendant's] arguments go
to the weight of the evidence and not to its
admissibility.  We conclude that the trial court erred
when it excluded Grimm's opinion on causation.
		"* * * * * 
	"[W]ithout Grimm's testimony as to the causation for
the neurological disorders, plaintiff may have been
unable to effectively rebut [defendant's] theory of the
case that she suffered from fibromyalgia.
		"In summary, the issue of causation was strongly
contested throughout the trial with experts differing
about whether the silicone that leaked from the
implants was capable of causing plaintiff's complaints. 
The trial court's ruling effectively prevented
plaintiff from offering testimony from a key witness
about the issue of causation and that ruling may have
affected the jury's view of the rest of plaintiff's
evidence in light of the requirement that plaintiff had
to prove her allegations by a preponderance of the
evidence.  On this record, we cannot say that there is
'little likelihood' that the trial court's ruling
affected plaintiff's case, and we conclude that a new
trial is necessary."	
Id. at 430-31.
II.  DISCUSSION

A.	Standard of Review
		At the threshold, we must determine the standard of
review.  Defendants argue that this court should review the trial
court's ruling for an abuse of discretion. (7)  Plaintiff argues
that the question whether scientific evidence is admissible is
reviewed for errors of law.  We agree with plaintiff.
		In State v. Brown, 297 Or 404, 687 P2d 751 (1984), this
court considered whether polygraph evidence was admissible.  The
court concluded that, "[n]otwithstanding the usual deference to
trial court discretion, we as an appellate court retain our role
to determine the admissibility of scientific evidence under the
Oregon Evidence Code."  Id. at 442.  In O'Key, this court
considered the admissibility of the horizontal gaze nystagmus
(HGN) test to show that a defendant was intoxicated.  The court
stated that "[t]he validity of proffered scientific
evidence * * * is a question of law * * *."  321 Or at 309 n 35.
The O'Key court explained:
		"Although this court typically is deferential to a
trial court's findings of preliminary facts under OEC
104(1), good reasons exist to modify this approach in
the context of scientific evidence.  Unlike almost all
other preliminary fact questions made under OEC 104(1),
a large component of the decision surrounding
scientific evidence transcends individual cases.  In
the usual application of OEC 104(1), a trial court must
make a context-specific factual determination.  For
example, a trial court must find by a preponderance of
the evidence that a conspiracy existed before admitting
evidence under the exemption from the ban on hearsay
for statements made by a co-conspirator, OEC
801(4)(b)(E), and the trial court must similarly find
that a hearsay declarant is 'unavailable' under OEC
804(1) for purposes of the statement against penal
interest exception to the hearsay rule, OEC 804(3)(c). 
Because those preliminary facts are specific to the
case before the trial court and do not repeat
themselves in the same form in other cases, substantial
deference to the trial court as factfinder logically
flows out of the trial court's close proximity to the
matter.  When the preliminary facts are not
case-specific, little or no deference to the trial
court's findings is appropriate.  The validity of
scientific knowledge does not change from court to
court; assessment of that knowledge should not change
from court to court.
		"Moreover, if evidentiary rulings as to the
admissibility of scientific evidence are reviewed with
deference to trial court discretion, inconsistent
decisions concerning the admissibility of scientific
evidence may go unchecked from one trial court to
another.  Such inconsistency may confound efforts to
provide uniformity under the Oregon Evidence Code."
Id. at 320 n 45 (citations omitted).  See also State v. Rogers,
330 Or 282, 308-15, 4 P3d 1261 (2000) (reviewing ruling that
expert witness was not qualified to testify about possible causes
of the defendant's frontal lobe dysfunction for errors of law). 
Accordingly, we review the trial court's ruling on Grimm's
testimony for errors of law. 
B.	Admissibility of Scientific Evidence
		In Brown, this court abandoned special tests for the
admissibility of scientific evidence in favor of resolving the
problem by relying on traditional evidence law as codified in the
Oregon Evidence Code.  297 Or at 408.  The admissibility of
scientific evidence implicates three provisions of the evidence
code.  OEC 401 defines relevant evidence as
	"evidence having any tendency to make the existence of
any fact that is of consequence to the determination of
the action more probable or less probable than it would
be without the evidence."	
(Emphasis added.)  OEC 702, which sets the standard for admission
of scientific evidence, provides:
		"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."	
OEC 403 permits the trial court to exclude relevant evidence
	"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 or needless presentation of cumulative
evidence."	
		According to Brown, expert testimony is admissible if
it is relevant under OEC 401, would assist the trier of fact
under OEC 702, and is not subject to exclusion under OEC 403. 
297 Or at 409.  
		Scientific evidence 
	"draws its convincing force from some principle of
science, mathematics and the like.  Typically, but not
necessarily, scientific evidence is presented by an
expert witness who can explain data or test results
and, if necessary, explain the scientific principles
which are said to give the evidence its reliability or
accuracy."  
Id. at 407-08.  This court also held:
	"In applying OEC 401, 702 and 403, this court must
identify and evaluate the probative value of the
evidence, consider how it might impair rather than help
the factfinder, and decide whether truthfinding is
better served by exclusion or admission."
Id. at 409.
		The Brown court instructed:	
	"In determining whether scientific evidence is
probative under OEC 401 and the relevancy and prejudice
analysis implicated in OEC 702's helpfulness standard,
we believe [that seven factors] * * * provide structure
and guidance * * *." 
Id. at 417.  Those factors are:
		"(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; and
		"(7) The extent to which the technique relies on
the subjective interpretation of the expert."  
Id. at 417. (8)  Those seven factors are not an exclusive checklist. 
Rather,
	"[t]he existence or nonexistence of these factors may
all enter into the court's final decision on
admissibility of the novel scientific evidence, but
need not necessarily do so.  What is important is not
lockstep affirmative findings as to each factor, but
analysis of each factor by the court in reaching its
decision on the probative value of the evidence under
OEC 401 and OEC 702."	
Id. at 417-18 (footnotes omitted).
		As noted in O'Key, a court should evaluate evidence
that purports to be scientific to ensure that it is
scientifically valid:
		"Evidence perceived by lay jurors to be scientific
in nature possesses an unusually high degree of
persuasive power.  The function of the court is to
ensure that the persuasive appeal is legitimate.  The
value of proffered expert scientific testimony
critically depends on the scientific validity of the
general propositions utilized by the expert. 
Propositions that a court finds possess significantly
increased potential to influence the trier of fact as
scientific assertions, therefore, should be supported
by the appropriate scientific validation.  This
approach 'ensure[s] that expert testimony does not
enjoy the persuasive appeal of science without
subjecting its propositions to the verification
processes of science.'"	
321 Or at 291-92 (footnote and citations omitted).  
C.	Application of Legal Principles to this Case
		Plaintiff argues that the Brown and O'Key standards for
admission of scientific evidence should not apply to Grimm's
testimony, because his testimony "does not involve the
application of scientific tests or statistical calculation, such
as polygraph machines or DNA testing, where concerns regarding
unfair prejudice and usurpation of the jury's role require a
showing of scientific reliability of an expert's underlying
methodology or process."  Plaintiff's concerns might be
appropriate in determining to what extent to apply the Brown and
O'Key factors.  See O'Key, 321 Or at 305 (multifactor inquiry is
flexible; ultimate concern is scientific validity); Brown, 297 Or
at 417 (factors "provide structure and guidance," but are not a
checklist).  However, plaintiff's concerns do not place Grimm's
testimony entirely beyond the reach of Brown and O'Key.  A jury
is likely to believe that a doctor's testimony about medicine is
a scientific assertion and, therefore, the proponent of the
testimony must show that it is scientifically valid.  
		Evidence is scientific when it "draws its convincing
force from some principle of science, mathematics and the like." 
Brown, 297 Or at 407.  "Propositions that a court finds possess
significantly increased potential to influence the trier of fact
as scientific assertions, therefore, should be supported by the
appropriate scientific validation."  O'Key, 321 Or at 292. 
Expert testimony regarding scientific evidence must bear a valid 
connection to the pertinent inquiry.  The reliability of such
expert testimony turns on whether it is scientific knowledge,
which is determined by evaluating its scientific validity.
		Clinical diagnoses bear the marks of science.  A
medical doctor gathers information from a patient to develop a
working diagnosis (a hypothesis), then uses that working
diagnosis to gather further information or to specify tests that
will confirm or refute the working diagnosis.  Reference Guide on
Medical Testimony at 463-64.  
		"The goal of the clinician is to arrive at a
diagnosis that can be used to develop a rational plan
for further investigation, observation, or treatment,
and ultimately to predict the course of the patient's
illness * * *.  To do this, the clinician must verify
or validate the diagnostic hypothesis."
Id. at 464.  See also O'Key, 321 Or at 292 ("The scientific
method is a validation technique, consisting of the formulation
of hypotheses, followed by observation or experimentation to test
the hypotheses."). 
		This court previously has indicated that scientific
evidence is subject to the requirements of Brown and O'Key, even
though the science involved is not "hard" science.  The O'Key
court held that the state's evidence in that case was scientific,
because it involved the premise that alcohol affected the
automatic tracking mechanisms of the eyes.  321 Or at 295; see
also State v. Milbradt, 305 Or 621, 630-31, 756 P2d 620 (1988)
(psychological syndrome evidence is a form of scientific
evidence). 
		The question in this case is whether Grimm was entitled
to testify about his opinion that silicone caused plaintiff's
neurological conditions.  In this inquiry, we focus on Grimm's
methodology, not on his conclusions.  See O'Key, 321 Or at 305
(focus must be solely on principles and methodology, not on the
conclusions that they generate).  After reviewing the record in
this case, we conclude that Grimm's methodology was
scientifically valid.  Thus, Grimm was entitled to offer his
opinion.
		The process of determining whether a substance causes a
disease overlaps numerous areas of study.  Epidemiology (9) is
informed by clinical medicine:
		"'While epidemiologic information is at times
derived from a much wider spectrum of biologic and
medical disciplines, these three -- clinical medicine,
pathology and biostatistics -- have almost universal
application in epidemiology.  Indeed, epidemiology may
be thought of as the joint application of the three in
the search for further understanding of disease
etiology.'"
George W. Conk, Against the Odds:  Proving Causation of Disease
with Epidemiological Evidence, 3 Shepard's Expert and Sci
Evidence Q 103, 120 (Summer 1995) (quoting Brian McMahon and
Thomas F. Pugh, Epidemiology, Principles and Methods (1970))
(emphasis added).
		Case reports based on clinical observations have
recognized value in epidemiological research:
		"Case reports lack controls and thus do not
provide as much information as controlled
epidemiological studies do.  However, case reports are
often all that is available on a particular subject
because they usually do not require substantial, if
any, funding to accomplish, and human exposure may be
rare and difficult to study.  Causal attribution based
on case studies must be regarded with caution. 
However, such studies may be carefully considered in
light of other information available, including
toxicological data."	
Reference Guide on Medical Testimony at 475 (emphasis added;
footnotes omitted).
		"There plainly is a hierarchy to these different
indirect forms of toxic effect evidence.  Epidemiology
is at the top, and structural similarity, in vitro
testing, and case reports are at the bottom.  Yet any
one of these forms of evidence may have some utility in
attempting to ascertain whether a causal connection
exists."
Michael D. Green, Expert Witnesses and Sufficiency of Evidence in
Toxic Substances Litigation:  The Legacy of Agent Orange and
Bendectin Litigation, 86 Nw U L Rev 643, 658 (1992).  An opinion
drawn from only case reports can be troublesome, because it
involves post hoc, ergo propter hoc (after this, therefore
because of this) reasoning:
  	"[S]ome children who live near power lines develop
leukemia; but does exposure to electrical and magnetic
fields cause this disease?  The anecdotal evidence is
not compelling because leukemia also occurs among
children who have minimal exposure to such fields.  It
is necessary to compare disease rates among those who
are exposed and those who are not.  If exposure causes
the disease, the rate should be higher among the
exposed, lower among the unexposed."
David H. Kaye and David A. Freedman, Reference Guide on
Statistics, 91, in Reference Manual on Scientific Evidence 
(footnote omitted).  However, case reports sometimes are
sufficient in and of themselves to establish causation. 
"Occasionally, when the effect of the agent is powerful enough,
scientists will tentatively accept case reports as sufficient to
establish a causal relation."  Green, 86 Nw U L Rev at 658.  Such
was the case with the drug Thalidomide, which caused an enormous
increase in birth defects.  Id. at 658 n 68. 
		The Vaccine Safety Committee of the Institute of
Medicine, National Academy of Sciences, also confirms that case
reports may serve as a basis for finding causation:
		"Although Can It? causality is usually addressed
from epidemiologic studies, an affirmative answer can
occasionally be obtained from individual case reports. 
Thus, if one or more cases have clearly been shown to
be caused by a vaccine (i.e., Did It? can be answered
strongly in the affirmative), then Can It? is also
answered, even in the absence of epidemiologic data. 
In several circumstances, for example, the committee
based its judgment favoring acceptance of a causal
relation solely on the basis of one or more convincing
case reports."
Kathleen R. Stratton, Cynthia J. Howe, and Richard B. Johnston,
Jr., eds, Adverse Events Associated with Childhood Vaccines: 
Evidence Bearing on Causality, 22 (1994) (last emphasis added).
		On this record, the "testability," or "falsifiability,"
factor is met. (10)  Any scientist can check Grimm's testing methods
and the clinical history of each of his patients.  Moreover,
Grimm's results also can be tested (another neurologist could
test women with silicone breast implants to see if they had the
same neurological conditions identified by Grimm).  Grimm's
hypothesis is capable of being falsified; that is, evidence may
be introduced to disprove his hypothesis.  See O'Key, 321 Or at
303 (science is based on testing hypotheses to see if they can be
falsified).  
		Although Grimm's hypothesis has not been tested by
others, that is, in part, because his work is new.  OEC 702 does
not preclude the admission of novel scientific evidence.  If it
is otherwise scientifically valid, a novel conclusion is
admissible.  O'Key, 321 Or at 302.  
		"The chief difficulty with novelty as a limitation
is * * * that it too strongly suggests a focus upon the
subject matter of the testimony as opposed to the real
matter of concern, the particular general propositions
relied upon by the witness." 
O'Key, 321 Or at 293 n 9 (quoting John William Strong, Language
and Logic in Expert Testimony:  Limiting Expert Testimony by
Restrictions of Function, Reliability, and Form, 71 Or L Rev 349,
367 (1992)).
		Grimm testified that he performed "a classic
neurological examination" on each of the women in his study
group.  Grimm's hypothesis is based on his own experiences and
observations, as well as on scientific methodology.  It was
tested by his evaluation of about 50 patients, most of whom
exhibited "unique" symptoms and conditions similar to those of
plaintiff.  All had been exposed to silicone from breast
implants.  Grimm conducted his evaluations by using neurological
examination techniques generally accepted by the scientific
community and with an error rate of five to seven percent.  In
each case, Grimm made personal observations and conducted a
medical record review.  He proceeded in conjunction with other
specialists involved in the women's care.  Grimm also studied the
scientific and medical literature about silicone-related
subjects.
		Grimm eliminated other potential causes of plaintiff's
conditions through differential diagnosis, which is a generally
accepted form of scientific inquiry.
		The trial judge expressed concern that Grimm had not
use a questionnaire.  A medical doctor does not need to use a
questionnaire to develop a patient's clinical history.  In
allowing Grimm to testify at length about his study, the trial
judge at least implicitly recognized that fact. 
		Grimm's study and conclusions had not been subjected to
peer review and had not been published.  However, neither peer
review nor publication is a sine qua non for the admissibility of
scientific evidence.  See O'Key, 321 Or at 304 ("In some cases
valid but innovative theories or propositions will not have been
published, either because they are too particular, too new, or of
limited interest.").  Publication or lack thereof in a peer-reviewed journal is a relevant, though not dispositive,
consideration in assessing the scientific validity of a
particular technique or methodology on which an opinion is based. 
Id.  The study underlying Grimm's opinion about causation had not
been accepted by the scientific community, but that is not to say
that the scientific community had rejected that study.  
		A conclusion about causation ultimately is a
qualitative decision.  See, e.g., Reference Guide on Epidemiology
at 375 ("While the drawing of causal inferences is informed by
scientific expertise, it is not a determination that is made by
using scientific methodology.").  The rate-of-error factor does
not always require the introduction of statistical evidence.  See
O'Key, 321 Or at 313 (concluding under that factor that the HGN
test is "a fairly reliable indicator of alcohol impairment"); cf.
Brown, 297 Or at 433 and 438 (polygraph evidence was probative
despite fact that there could be no judgment of validity or
potential rate of error).
		The trial court expressed concern that Grimm could not
explain the mechanism causing "patterns and complaints of
tingling in [the] fingers and so forth * * *" of his study group.
"But," as Sir Austin Bradford Hill stated regarding the causation
of disease, "this is a feature I am convinced we cannot demand. 
What is biologically plausible depends upon the biological
knowledge of the day."  Hill, The Environment and Disease: 
Association or Causation?, 58 Proc R Soc Med 295, 298 (1965). 
There are many generally accepted hypotheses in science for which
the mechanism of cause and effect is not understood fully. 
Grimm's inability to explain the mechanism of plaintiff's
condition goes to weight, not to admissibility.  
		The trial court also expressed concern that Grimm
declined to label the two conditions that plaintiff suffered as a
"disease."  However, Grimm adequately explained his reluctance to
label plaintiff's conditions prematurely, and his explanation in
no way cast doubt on the existence of the neurological conditions
that he found in plaintiff. 
	III.  CONCLUSION

		The question before this court on review is whether the
trial court erred in prohibiting Grimm from testifying that, in
his opinion, plaintiff's neurological symptoms probably were
caused by silicone exposure from her breast implants.  On this
record, we conclude that the court should have admitted that
evidence.  Grimm's methodology withstood scrutiny under the Brown
and O'Key factors, and that methodology supported his proffered
opinion testimony.  Grimm's opinion regarding causation was
relevant and probative.  We reject defendant's proposed rule of
law that an expert opinion on causation based on anything other
than statistically significant, peer-reviewed, published
epidemiological studies is inadmissible.  We also agree with the
Court of Appeals, 152 Or App at 430, that Grimm's opinion
testimony about causation would have been helpful to the jury and
that there is nothing in his excluded testimony that would have
caused unfair prejudice or confusion, or that would have misled
the jury.
  		In the past, this court has stated that a published
decision affirming the admissibility of certain forms of
scientific evidence will mean that the proponent of the evidence
need not lay a scientific foundation for it again.  Lyons, 324 Or
at 280 n 31;  O'Key, 321 Or at 293.  In this case, however, our
conclusion regarding the admissibility of Grimm's testimony is
not necessarily binding on retrial:
	"The scientific enterprise always must remain open to
reassessing the validity of past judgments as new
evidence develops."  
Reference Guide on Epidemiology at 374.  Grimm admitted that his
studies were not complete.  In the five years that have passed
since the trial, Grimm may have developed additional evidence
that either confirms or refutes his earlier conclusion.  At a
retrial, therefore, and on appropriate motion, plaintiff may be
called on to satisfy the requirements of Brown and O'Key. 
		The decision of the Court of Appeals is affirmed.  The
judgment of the circuit court is reversed, and the case is
remanded to the circuit court for further proceedings.

1. The breast implants were manufactured and sold by
Heyer-Schulte, a division of American Hospital Supply Corporation
(AHSC).  Dow Corning supplied Heyer-Schulte with the silicone
material.  In 1984, AHSC merged into the Baxter Healthcare
Corporation and Baxter International, Inc.  Willamette Falls
Hospital performed a mammogram on plaintiff that allegedly caused
one implant to deflate partially.  Plaintiff originally brought
claims against the Baxter entities, Dow Corning, and Willamette
Falls Hospital.  Before trial, the court dismissed Dow Corning
and Willamette Falls Hospital from the case.

2. Fibromyalgia is "chronic pain in muscles and soft
tissues surrounding joints."  Taber's Cyclopedic Medical
Dictionary, 728 (17th ed 1993).  Defendant's expert diagnosed
plaintiff with fibromyalgia.  He explained that "[f]ibromyalgia
is what we call a generalized pain condition * * * marked by
generalized aching.  It's not just localized, but tends to be
aching all over."

3. Neurology is "[t]he branch of medical science concerned
with the various nervous systems (central, peripheral, and
autonomic, plus the neuromuscular junction and muscle) and its
disorders."  Stedman's Medical Dictionary, 1202 (26th ed 1995). 
Neurophysiology is the physiology of the nervous system.  Id. at
1204.

4. In O'Key, the court stated that, "[w]hen proffered
scientific evidence raises issues of scientific validity, those
issues should be addressed by the trial court in a separate OEC
104(1) hearing, preferably in advance of trial."  321 Or at 307 n
29.  OEC 104(1) provides:
		"Preliminary questions concerning the
qualification of a person to be a witness, the
existence of a privilege or the admissibility of
evidence shall be determined by the court, subject to
the provisions of subsection (2) of this section.  In
making its determination the court is not bound by the
rules of evidence except those with respect to
privileges."
Under OEC 104(1), the trial judge must decide whether the
proffered evidence satisfies the minimum threshold of relevance
required by OEC 401.  OEC 401 requires a very low threshold of
relevance.  "Evidence that increases, even slightly, the
probability of the existence of a material fact is relevant
evidence."  State v. Lyons, 324 Or 256, 270, 924 P2d 802 (1996).

5. Grimm testified that the word "vestibular" refers to
part of the inner ear:  "The inner ear is divided into two parts: 
one, the balance part, the vestibular part; the other is the
hearing part."

6. Differential diagnosis is:
	"[t]he determination of which of two or more diseases
with similar symptoms is the one from which the patient
is suffering, by a systematic comparison and
contrasting of clinical findings."
Stedman's Medical Dictionary at 474.

7. That is the approach currently being taken in federal
courts.  See, e.g., General Electric Co. v. Joiner, 522 US 136,
143, 118 S Ct 512, 139 L Ed 2d 508 (1997) ("admissibility of
expert testimony * * * is reviewable under the abuse-of-discretion standard").

8. In a footnote, the Brown court listed 11 additional
factors that the court may consider:
		"(1) The potential error rate in using the
technique;
		"(2) The existence and maintenance of standards
governing its use;
		"(3) Presence of safeguards in the characteristics
of the technique;
		"(4) Analogy to other scientific techniques whose
results are admissible;
		"(5) The extent to which the technique has been
accepted by scientists in the field involved;
		"(6) The nature and breadth of the inference
adduced;
		"(7) The clarity and simplicity with which the
technique can be described and its results explained;
		"(8) The extent to which the basic data are
verifiable by the court and jury;
		"(9) The availability of other experts to test and
evaluate the technique;
		"(10) The probative significance of the evidence
in the circumstances of the case; and
		"(11) The care with which the technique was
employed in the case."
Brown, 297 Or at 417 n 5.
		In O'Key, 321 Or at 306 n 28, the court recognized
additional factors that may be considered in determining the
admissibility of proffered expert scientific testimony.

9. "Epidemiology is the field of public health and
medicine that studies the incidence, distribution, and etiology
of disease in human populations."  Michael D. Green, D. Michal
Freedman, and Leon Gordis, Reference Guide on Epidemiology, 335,
in Reference Manual on Scientific Evidence (hereinafter Reference
Guide on Epidemiology).

10. One of the factors mentioned in Brown is the
availability of other experts to test and evaluate the technique. 
297 Or at 417 n 5.  The United States Supreme Court has used the
terms falsifiability, refutability, and testability.  Daubert v.
Merrell Dow Pharmaceuticals, Inc., 509 US 579, 593, 113 S Ct
2786, 125 L Ed 2d 469 (1993).