* After examining the briefs and appellate record, this panel has determined

unanimously that oral argument would not materially assist the determination of

this appeal. See Fed. R. App. P. 34(a)(2); 10th Cir. R. 34.1(G). The case is

therefore ordered submitted without oral argument. This order and judgment is

not binding precedent, except under the doctrines of law of the case, res judicata,

and collateral estoppel. It may be cited, however, for its persuasive value

consistent with Fed. R. App. P. 32.1 and 10th Cir. R. 32.1. 

FILED

United States Court of Appeals

Tenth Circuit

June 17, 2009

Elisabeth A. Shumaker

Clerk of Court

UNITED STATES COURT OF APPEALS

FOR THE TENTH CIRCUIT

EDWARD RONWIN,

Plaintiff-Appellant,

v.

BAYER CORPORATION, an Indiana

corporation, doing business as Bayer

Pharmaceutical Division,

Defendant-Appellee.

No. 08-8089

(D.C. No. 2:01-CV-00172-WFD)

(D. Wyo.)

ORDER AND JUDGMENT*

Before KELLY, McKAY, and BRISCOE, Circuit Judges.

Edward Ronwin appeals pro se the district court’s grant of summary

judgment in favor of Bayer Corporation on his claims for negligence, strict

liability, and breach of implied warranty. Exercising jurisdiction under 28 U.S.C.

§ 1291, we affirm.
1 “Rhabdo[myolysis] is an acute, fulminating, potentially fatal disease of the

skeletal muscle, which entails destruction of skeletal muscle.” In Re Baycol

Prods. Litig., 218 F.R.D. 197, 201 n.1 (D. Minn. 2003).

2 Plaintiff originally filed his complaint in state court in Wyoming. Bayer

removed the case to the United States District Court for the District of Wyoming. 

(continued...)

-2-

Background

Dr. Ronwin filed a complaint against Bayer in September 2001, alleging

that he was injured by cerivastatin, a prescription drug in the “statin” family that

was manufactured and sold by Bayer under the name “Baycol.” The United

States Food and Drug Administration (FDA) first approved Baycol for the

treatment of high cholesterol in 1997. Plaintiff began taking Baycol for that

purpose on or about January 10, 2001, when he was almost 77 years old. He

alleges that a short time later he began experiencing a number of physical

symptoms, including pain in his left shoulder, thighs, and back, blurred vision,

and gait problems. He stopped taking Baycol on or about August 8, 2001. He

claims that his blurred vision and gait problems receded after he ceased taking

Baycol, but that his other symptoms persisted. Dr. Ronwin was diagnosed in

2003 with a torn left rotator cuff, which he had surgically repaired. 

Bayer voluntarily removed Baycol from the market on August 8, 2001,

citing a risk of rhabdomyolysis1

 as a serious, potentially fatal adverse effect of the

drug. Dr. Ronwin and thousands of other plaintiffs sued Bayer, claiming that

various injuries resulted from their ingestion of Baycol.2

 As of 2003, Bayer had
2

(...continued)

In January 2002 the case was conditionally transferred by the Judicial Panel on

Multidistrict Litigation to the United States District Court for the District of

Minnesota (hereafter “MDL case”). After pretrial proceedings were completed,

including briefing on Bayer’s summary judgment motion, plaintiff’s case was

transferred back to the district court in Wyoming in 2007.

-3-

settled close to 1,000 of the claims involving Baycol. See In re Baycol Prods.

Litig., 218 F.R.D. 197, 210 (D. Minn. 2003).

In support of his claims, plaintiff proffered his own expert testimony and

the expert testimony of Dr. Raul G. Reyes, as summarized in expert reports

submitted to the district court. After discovery was completed, Bayer filed a

summary judgment motion arguing there was no evidence establishing that Baycol

caused plaintiff to suffer any injury. More specifically, Bayer contended that

plaintiff’s proffered expert testimony was inadmissible under Federal Rule of

Evidence 702 and Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579

(1993), because neither witness was qualified to offer an expert opinion and their

methodologies were not reliable. The district court granted Bayer’s motion,

excluding plaintiff’s proffered expert testimony and granting summary judgment

in favor of Bayer on all claims.

Applicable Law and Standards of Review

In this diversity action “the substantive law of the forum state governs the

analysis of the underlying claims, including specification of the applicable

standards of proof, but federal law controls the ultimate, procedural question
-4-

whether [summary judgment] is appropriate.” Specialty Beverages, L.L.C. v.

Pabst Brewing Co., 537 F.3d 1165, 1175 (10th Cir. 2008). Thus, we apply

federal law in reviewing de novo the district court’s grant of summary judgment

in this case. See Hollander v. Sandoz Pharm. Corp., 289 F.3d 1193, 1214

(10th Cir. 2002). Summary judgment is appropriate “if the pleadings, the

discovery and disclosure materials on file, and any affidavits show that there is no

genuine issue as to any material fact and that the movant is entitled to judgment

as a matter of law.” Fed. R. Civ. P. 56(c).

The district court’s grant of summary judgment in favor of Bayer rested on

two antecedent rulings. First, the district excluded the testimony of both of

plaintiff’s experts. “The admissibility of expert testimony is governed by Rule

702 of the Federal Rules of Evidence.” United States v. Benally, 541 F.3d 990,

994 (10th Cir. 2008), cert. denied, 129 S. Ct. 1020 (2009).

We review de novo the question of whether the district court

performed its gatekeeper role and applied the proper legal standard in

admitting an expert’s testimony. We then review for abuse of

discretion the trial court’s actual application of the gatekeeper

standard in deciding whether to admit or exclude an expert’s

testimony.

Miller v. Pfizer, Inc., 356 F.3d 1326, 1335 (10th Cir. 2004) (quotation and

brackets omitted). In reviewing a district court’s application of the second step of

this standard, we afford substantial deference to a court’s exclusion of expert

opinion evidence under Daubert. Hollander, 289 F.3d at 1204. “Under the abuse
3 Plaintiff contends that we should apply a de novo standard of review to the

district court’s exclusion of expert testimony because the court’s evidentiary

ruling served as the definitive ground for its grant of summary judgment. The

Supreme Court rejected a similar argument in General Electric Co. v. Joiner,

522 U.S. 136, 142-43 (1997), holding that a district court’s decision on the

admissibility of expert testimony is reviewed for an abuse of discretion, even

where that ruling is “outcome determinative” for purposes of summary judgment.

-5-

of discretion standard, a trial court’s decision will not be disturbed unless the

appellate court has a definite and firm conviction that the lower court made a

clear error of judgment or exceeded the bounds of permissible choice in the

circumstances.” Id. (quotation omitted).3

In its second ruling leading to its grant of summary judgment, the district

court held that, under Wyoming law, plaintiff was required to present expert

testimony in order to establish that Baycol caused his injuries. Plaintiff does not

challenge the district court’s application of Wyoming law in deciding this issue. 

Exclusion of Expert Testimony

The proponent of expert testimony bears the burden of showing that its

proffered expert’s testimony is admissible. Ralston v. Smith & Nephew Richards,

Inc., 275 F.3d 965, 970-71 n.4 (10th Cir. 2001). F.R.E. 702 “imposes upon the

trial judge an important ‘gate-keeping’ function with regard to the admissibility

of expert opinions.” Ralston, 275 F.3d at 969. In this role, a district court should

apply a two-step analysis, determining first whether an expert is qualified to

render an opinion by “‘knowledge, skill, experience, training, or education,’” and
-6-

second, whether the expert’s opinions are “‘reliable’” under Daubert. Id.

(quoting F.R.E. 702). “Reliability is determined by assessing whether the

reasoning or methodology underlying the testimony is scientifically valid.” 

Hollander, 289 F.3d at 1204 (quotation omitted).

Trial courts generally apply four factors in assessing the reliability of an

expert’s methodology:

(1) whether the opinion at issue is susceptible to testing and has been

subjected to such testing; (2) whether the opinion has been subjected

to peer review; (3) whether there is a known or potential rate of error

associated with the methodology used and whether there are

standards controlling the technique’s operation; and (4) whether the

theory has been accepted in the scientific community.

Id. at 1205. These factors are nonexclusive, “and district courts applying Daubert

have broad discretion to consider a variety of other factors.” Id. But

[r]egardless of the specific factors at issue, the purpose of the

Daubert inquiry is always the same: to make certain that an expert,

whether basing testimony upon professional studies or personal

experience, employs in the courtroom the same level of intellectual

rigor that characterizes the practice of an expert in the relevant field. 

Id. at 1205-06 (quotation and brackets omitted).

Plaintiff’s Proffered Expert Testimony

Plaintiff proffered Dr. Reyes and himself as expert witnesses on causation. 

Although Dr. Reyes is a surgeon with over fifty years of experience, he admitted

in his deposition that he had never prescribed statin drugs and that he was

unaware of any published medical literature linking statins, or Baycol in
4 With respect to plaintiff’s other claimed injuries, Dr. Reyes’s expert report

concluded only that his symptoms “may be related to his ingestion of Baycol.” 

Aplee. App., Vol. I at 286.

-7-

particular, to rotator cuff injuries. After reviewing a small portion of plaintiff’s

medical records, Dr. Reyes submitted an expert report concluding that:

The medical records clearly reveal that Dr. Ronwin suffered a left

shoulder rotator cuff tear which required corrective surgery and, in

view of the undisputed propensity of Baycol to disrupt body function

along with an absence of any other traumatic event in Dr. Ronwin’s

case, it is my medical opinion that in view of the lack of medical

history of any injury to this shoulder that there is a high probability

that this injury was caused by Baycol ingestion for a period of seven

(7) months.

Aplee. App., Vol. I at 286.4

Dr. Ronwin purports to be an expert on the biochemical composition of

Baycol and its effect on the human body. He received B.S. and M.S. degrees in

chemistry in 1949 and 1950, and a Ph.D. in biochemistry in 1952. He worked in

the fields of chemistry and biochemistry until 1971, during which time he

authored or co-authored numerous published scientific papers. He entered law

school in 1971, then practiced law for twenty years. At the time he submitted his

expert report in opposition to Bayer’s summary judgment motion, Dr. Ronwin had

not actively worked as a scientist in more than 30 years, but he had maintained

his memberships in three major scientific societies, he continued to read scientific

publications, and he taught one chemistry overview course in 2001.
-8-

In his expert report Dr. Ronwin concluded that the injuries he suffered “are

related to and caused by [his] ingestion of Baycol whose chemical structure can

give rise to flouride ion which can, in turn, cause injury to numerous body

components, proteins and tissues including the protein collagen in tendons and in

rotator cuff tendons.” Aplee. App., Vol. II at 509. In support of this theory, he

cited a book and a number of scientific papers addressing the effects of

flouridated drinking water on various parts of the human body. In addition to

these writings, he also based his opinion on his “general store of personal,

biochemical knowledge.” Id. at 507.

Expert Qualifications

Applying the first step of the Rule 702 analysis, the district court held that

Drs. Reyes and Ronwin were not qualified by their knowledge, skill, experience,

training, or education to testify regarding a causal connection between Baycol

ingestion and plaintiff’s shoulder injury. The court noted Dr. Reyes’s lack of any

practical experience or training with respect to Baycol or statins in general and

Dr. Ronwin’s “lengthy departure from active research, publication, and teaching.” 

Aplee. App., Vol. II at 803. A district court has “wide discretion” in determining

whether a witness’s experience is sufficient to qualify him as an expert. United

States v. Arney, 248 F.3d 984, 991 (10th Cir. 2001). Dr. Ronwin contends that

Dr. Reyes’s extensive orthopedic surgery experience qualifies him to opine on the

cause of plaintiff’s rotator cuff tear. But we have specifically rejected the
-9-

contention that surgical experience alone is sufficient to qualify an expert to

testify regarding an issue “not within the reasonable confines of her subject area.” 

Ralston, 275 F.3d at 970 (holding district court did not abuse its discretion in

excluding testimony by board-certified orthopedic surgeon where she had no

practical, research, or publication experience regarding the subject matter of her

proffered expert testimony, see id. at 969-70). Nor did the district court abuse its

discretion in holding that Dr. Ronwin’s relevant practical experience in

biochemistry was too stale to qualify him to give an expert causation opinion in

this case. See Meyerhoff v. Michelin Tire Corp., 70 F.3d 1175, 1182 (10th Cir.

1995) (upholding exclusion of expert testimony based, in part, on proffered

witness’s absence from the relevant industry for over 30 years). Applying the

proper standard, we cannot conclude that the district court abused its discretion in

concluding that Drs. Reyes and Ronwin were not qualified to testify regarding

whether Baycol caused plaintiff’s injuries.

Methodologies

The district court also excluded plaintiff’s experts’ testimony on the

independent basis that their methodologies failed to satisfy any of the four

Daubert factors and were therefore not scientifically valid or reliable. First, we

reject plaintiff’s argument that his experts’ theories have been peer reviewed. His

primary contention, however, is that the district court erred in choosing to apply

the Daubert factors. Specifically, he argues that, because of the short time that
-10-

Baycol was sold, there will never be sufficient research to support a causation

conclusion, and further that “‘[t]he first several victims of a new toxic tort should

not be barred from having their day in court simply because the medical

literature, which will eventually show the connection between the victims’

condition and the toxic substance, has not yet been completed.’” Aplt. Opening

Br. at 18 (quoting Hollander, 289 F.3d at 1211). The record belies plaintiff’s

assertions: thousands of plaintiffs filed suits asserting that Baycol caused their

injuries; the district court in the MDL case required each plaintiff to submit an

expert report in support of his claim of causation; and plaintiff’s case had been

pending for seven years at the time the district court excluded his proffered expert

testimony. We cannot conclude that the district court exceeded the bounds of

permissible choice in deciding to apply the four Daubert factors in assessing the

reliability of Dr. Reyes’s and Dr. Ronwin’s methodologies.

Because the district court has discretion to consider a variety of

factors [in] assessing reliability under Daubert, and because, in light

of that discretion, there is not an extensive body of appellate case

law defining the criteria for assessing scientific reliability, we are

limited to determining whether the district court’s application of . . .

Daubert manifests a clear error of judgment or exceeds the bounds of

permissible choice in the circumstances.

Hollander, 289 F.3d at 1206.

Plaintiff asserts that the district court should have admitted Dr. Reyes’s

testimony, despite its failure to satisfy any of the Daubert factors, because a

reasonable differential diagnosis may be sufficient to validate a causation
5 Dr. Ronwin does not contend that he performed a differential diagnosis, or

even that he would be qualified to do so. 

6 “‘Differential diagnosis’ refers to the process by which a physician ‘rules

in’ all scientifically plausible causes of the plaintiff’s injury. The physician then

‘rules out’ the least plausible causes of injury until the most likely cause remains. 

The remaining cause is the expert’s conclusion.” Hollander, 289 F.3d at 1209

(citation and quotation omitted). We have emphasized that the remaining cause

must have been “ruled in” as scientifically plausible based upon reliable evidence. 

See id. at 1211. And this court has recognized that deficiencies in a particular

differential diagnosis can support a district court’s decision to exclude expert

testimony. See id. at 1212.

-11-

opinion.5

 See id. at 1211-12.6 Bayer argues that Dr. Reyes did not do a

differential diagnosis ruling out all other plausible causes of his shoulder injury,

including those that were identified by plaintiff’s own treating physicians. 

Plaintiff responds that Dr. Reyes implicitly did such an analysis with respect to

degenerative changes and his advanced age as likely causes of his rotator cuff

tear. He asserts that Dr. Reyes reviewed his medical records related to the

shoulder injury and was aware of his age, therefore Dr. Reyes must have

considered and ruled out these other factors as the cause of his injury, as opposed

to simply ignoring or overlooking them. But plaintiff admits that Dr. Reyes did

not rule out a third potential cause, and he fails to show that Dr. Reyes ruled in

Baycol as a scientifically plausible cause based upon reliable evidence. We

conclude that the district court did not abuse its discretion in failing to admit

Dr. Reyes’s expert testimony based upon his “implicit” differential diagnosis.
7 In that decision the district court specifically addressed plaintiff’s claims,

stating that “[c]ontrary to Plaintiff Ronwin’s assertions, whether Baycol caused

such injuries is beyond the understanding and experience of a lay person, and will

require a differential diagnosis.” In re Baycol Prods. Litig., 321 F. Supp. 2d at

1126-27.

-12-

Absent indicia of reliability based upon the Daubert factors or a valid

differential diagnosis, all that is left to support plaintiff’s experts’ causation

conclusions is their own ipse dixit. See Gen. Elec. Co., 522 U.S. at 146

(“[N]othing in either Daubert or the Federal Rules of Evidence requires a district

court to admit opinion evidence that is connected to existing data only by the ipse

dixit of the expert.”). The district court did not abuse its discretion in excluding

plaintiff’s proffered expert testimony.

Grant of Summary Judgment

Having excluded plaintiff’s proffered expert testimony, the district court

held that he presented no evidence demonstrating a causal link between his

ingestion of Baycol and his alleged injuries. In reaching this conclusion, the

court applied an earlier ruling in the MDL case that, because the Baycol litigation

involves complicated causation issues, all plaintiffs were required to present

expert testimony to prove injury and a causal connection. See In re Baycol Prods.

Litig., 321 F. Supp. 2d 1118, 1125-26 (D. Minn. 2004) (citing Sayer v. Williams,

962 P.2d 165, 167 (Wyo. 1998)).7

 Plaintiff does not identify any error in the

district court’s conclusion that, absent expert testimony on causation, summary
8 The cases from other circuits that plaintiff cites for the first time in his

reply brief do not squarely support that proposition in the context of this case. 

Therefore, in addition to being tardy, they are not persuasive. See Season-All

Indus., Inc. v. Turkiye Sise Ve Cam Fabrikalari, A.S., 425 F.2d 34, 39-40 (3d Cir.

1970) (holding that summary judgment should not be granted on the briefs

without oral argument unless court makes clear that affidavits must be filed with

the briefs); Ga. S. & Fla. Ry. Co. v. Atl. Coast Line R.R. Co., 373 F.2d 493,

496-98 (5th Cir. 1967) (addressing final judgment granted after court, without

prior notice, converted motion to dismiss into summary judgment motion and

(continued...)

-13-

judgment was appropriate. But he argues that summary judgment should be

reversed because the district court did not grant his request for oral argument on

Bayer’s motion. He contends that the court’s failure to grant him an oral hearing

is a violation of his rights under the First and Seventh Amendments.

Denial of Oral Argument

“The law is well-settled that summary judgment does not violate the

Seventh Amendment.” J.R. Simplot v. Chevron Pipeline Co., 563 F.3d 1102,

1117 (10th Cir. 2009). Nor does a “hearing” on a summary judgment motion

necessarily require oral argument. “Rather, the parties’ right to be heard may be

fulfilled by the court’s review of the briefs and supporting affidavits and

materials submitted to the court.” Geear v. Boulder Comm. Hosp., 844 F.2d 764,

766 (10th Cir. 1988). Plaintiff does not cite in his opening brief any case law

holding that a district court’s grant of summary judgment without an oral hearing

is constitutionally infirm, or otherwise denying a district court discretion to

decide a summary judgment motion without oral argument.8
8

(...continued)

granted summary judgment after preliminary injunction hearing); Dredge Corp. v.

Penny, 338 F.2d 456, 461-62 (9th Cir. 1964) (holding that district court could not

apply local rule to preclude oral argument); see also Stump v. Gates, 211 F.3d

527, 533 (10th Cir. 2000) (stating “court does not ordinarily review issues raised

for the first time in a reply brief”). 

9 Plaintiff raises two additional “issues” in his opening brief, which we

decline to address in detail. Whether Bayer “deliberately lie[d] to the court

below” and whether Bayer is a “criminal organization,” Aplt. Opening Br. at 2,

have no bearing on the basis for the district court’s grant of summary judgment in

Bayer’s favor.

-14-

In Geear we addressed the sufficiency of the parties’ written materials in

the absence of an oral hearing:

[T]he district judge examined the briefs and supporting materials to

evaluate the merits of the motion for summary judgment. Nothing in

the record suggests that the issues and evidence presented in this case

could not be addressed adequately in the form of written briefs with

accompanying affidavits, depositions and similar exhibits. Based

upon its review of the submitted materials, the court found that entry

of judgment was appropriate because there was no genuine issue of

fact, and the Defendant was entitled to judgment as a matter of law.

Thus, the court satisfied the “hearing” requirement of Rule 56.

844 F.2d at 766. The same reasoning applies here. Plaintiff does not identify any

legal or factual issue that he was unable to present sufficiently in his 71-page

brief in response to Bayer’s motion, such that oral argument was essential. We

conclude that the district court’s decision not to grant a hearing on Bayer’s

summary judgment motion was not an abuse of discretion. We therefore affirm

the district court’s grant of summary judgment in favor of Bayer.9
-15-

Conclusion

The judgment of the district court is AFFIRMED.

Entered for the Court

Paul J. Kelly, Jr.

Circuit Judge