Revised April 30, 2002

                  UNITED STATES COURT OF APPEALS
                       FOR THE FIFTH CIRCUIT
              _____________________________________

                           No. 01-30654
              _____________________________________


                        Thomas PIPITONE,
                      and Bonnie PIPITONE,

                                            Plaintiffs-Appellants,

                                  v.

                        BIOMATRIX, INC.,

                                            Defendant-Appellee.


       __________________________________________________

          Appeal from the United States District Court
              for the Eastern District of Louisiana
       __________________________________________________

                         April 18, 2002


Before GARWOOD, JOLLY, and DAVIS, Circuit Judges.

W. EUGENE DAVIS, Circuit Judge:

     Thomas Pipitone and his wife, Bonnie, brought suit against

Biomatrix, Inc. (“Biomatrix”), alleging that a product that

Biomatrix manufactures, known as Synvisc, caused Mr. Pipitone to

develop a salmonella infection in his knee after a physician

injected his knee with Synvisc.    The district court excluded the

testimony of the plaintiffs’ experts, Doctors Millet and Coco,

under the standard set forth in Daubert v. Merrell Dow
Pharmaceuticals, Inc..1      The district court concluded that

without the testimony of their two witnesses, the plaintiffs

could not establish their case and granted summary judgment in

favor of Biomatrix.       Because we conclude that the district court

abused its discretion in excluding the testimony of Dr. Coco, we

reverse the district court’s grant of summary judgment in favor

of Biomatrix and remand the case to the district court.

                                      I.

       In June 1999, Thomas Pipitone sought treatment from his

physician, Dr. Murray, for an ulcer that had developed on his

toe.       Because Pipitone was a 58 year-old, insulin-dependent

diabetic, Dr. Murray hospitalized Pipitone and placed him on

antibiotics as a precaution.       Dr. Chad Millet, an orthopedic

surgeon, examined Pipitone in the hospital and agreed with Dr.

Murray’s diagnosis and prescription of antibiotics.       Dr. Millet

continued treating Pipitone for the ulcer on his toe until

September 1999, when Dr. Millet noted that the ulcer was healing.

       In October 1999, Pipitone returned to Dr. Millet, this time

complaining of severe osteoarthritic pain in his knees.         Dr.

Millet specializes in joints, especially hips and knees, for

which he undertook an additional year of training at John Hopkins

Hospital.       Dr. Millet injected Pipitone’s left knee with

Cortisone in an attempt to alleviate the pain.


       1
               

(1993).

                                      -2-
     In November 1999, Pipitone suffered a stroke.    As a result,

when Pipitone returned to Dr. Millet on January 11, 2000, still

complaining of knee pain, he was no longer a candidate for knee

replacement surgery.    As an alternative to surgery, Dr. Millet

suggested treatment with Synvisc.

     Synvisc is a replacement synovial fluid manufactured by

Biomatrix.    Synvisc is made from rendered rooster combs, which

are bathed in formaldehyde for a full day and then subjected to

other chemical and detergent treatments.    The product is put

through a sterile filtration system and into syringes.    Biomatrix

packages Synvisc in boxes of three, factory-sealed syringes to be

administered by injection directly into the knee once a week for

three weeks.    When injecting Synvisc, the doctor supplies only

the needle.

     The Food and Drug Administration (“FDA”) granted Biomatrix’s

pre-market approval application in August of 1997, and classified

Synvisc as a “Class III” device for purposes of the Medical

Devices Act.    Over four million syringes of Synvisc have been

manufactured since 1998, but it is unclear from the summary

judgment record how many have actually been consumed.

     Pipitone decided to go forward with the Synvisc treatment.

He filled the prescription for Synvisc at a Walgreen’s pharmacy

and returned to Dr. Millet’s office on the morning of January 25,

2000, to receive the injection.     Dr. Millet’s nurse, who was not



                                  -3-
scrubbed down, opened the Synvisc package and one of the shrink-

wrapped syringes inside.    She also opened the packaging for the

needle and aspiration syringe, both of which Dr. Millet’s office

supplied.    The nurse then attached the needle, still in its

sterile sheath, to the empty aspiration syringe, and placed all

of these items on an injection tray next to unsterile gauze.

     Wearing unsterile gloves, Dr. Millet prepared Pipitone’s

knee with an antibiotic cleanser and then with alcohol.

Following Biomatrix’s instructions, Dr. Millet inserted the

needle attached to the empty aspiration syringe into Pipitone’s

knee and withdrew a small amount of synovial fluid.    He noted

that the fluid was clear and normal in appearance and indicated

no sign of infection.    Dr. Millet then detached the fluid-filled

aspiration syringe from the needle, which remained in place in

Pipitone’s knee, removed the rubber tip from the Synvisc syringe,

and attached the Synvisc syringe to the needle.    Dr. Millet then

injected the Synvisc and removed the needle.    He placed a bandage

over the entry site, and Pipitone went home.

     Later that evening, Pipitone began having severe pain in his

knee.   His wife took his temperature, which was 101 degrees, but

they did not report these symptoms to a doctor at that time

because they believed that they were attributable to the

injection.    As Pipitone’s knee pain worsened, the Pipitones made

several attempts to contact Dr. Millet’s office and succeeded in



                                 -4-
meeting him on the morning of January 27, two days after the

injection.    Dr. Millet aspirated some of the synovial fluid from

Pipitone’s knee and found that it was cloudy and turbid,

indicating infection.   Dr. Millet immediately hospitalized

Pipitone and drained Pipitone’s infected knee completely.     The

hospital laboratory tested the fluid from Pipitone’s knee and

discovered that the infection was salmonella, which is extremely

rare in joints.

     Because the culture showed such a rare infection, Dr. Millet

asked Dr. Jeffrey Coco, a physician who limits his practice to

infectious diseases, to examine Pipitone.   When Dr. Coco

evaluated Pipitone in the hospital, he found that Pipitone had no

fever, chilled sweats, diarrhea, nausea, or vomiting.    Dr. Coco

also found that the ulcer on Pipitone’s toe had scabbed over and

was healing nicely.   Dr. Coco ordered a second check of the

synovial fluid from Pipitone’s knee, but the laboratory had

already rechecked the fluid due to the rarity of the result.     The

second test showed again that the infection was salmonella.

     When Biomatrix was informed of Pipitone’s infection, it

tested the other two syringes in the Synvisc package that

Pipitone purchased and found no evidence of salmonella.     It also

tested the twenty syringes held back from the production lot that

had included the Synvisc sold to Pipitone and found no

salmonella.



                                 -5-
     In April 2000, the plaintiffs filed suit against Biomatrix

and Wyeth Laboratories2 in Louisiana state court alleging causes

of action arising under state tort, products liability, and

redhibition laws.   The defendants timely removed the suit to

federal court.

     In February 2001, the Pipitones filed a medical malpractice

action against Dr. Millet.   After taking Dr. Millet’s and Dr.

Coco’s depositions, however, the plaintiffs were persuaded that

fault must have been in Biomatrix’s manufacture of the Synvisc.

The plaintiffs then voluntarily dismissed their action against

Dr. Millet.

     In April 2001, the district court held a hearing to consider

Biomatrix’s motion for summary judgment.   The court first granted

defendant’s motion in limine to exclude the testimony of Dr.

Millet and Dr. Coco as unreliable under Daubert.   The district

court then held that the Medical Devices Act preempted most of

plaintiffs’ state law claims.3   The only claims that survived

preemption were the plaintiffs’ claims for manufacturing defect



     2
          The plaintiffs voluntarily dismissed Wyeth Laboratories
without prejudice on March 21, 2001.
     3
          Specifically, the district court held that the MDA
preempted plaintiffs’ claims for design defect, inadequate warning,
and nonconformity with express warning under the LPLA, and
therefore, dismissed these claims with prejudice. The plaintiffs
had already moved to voluntarily dismiss these claims without
prejudice, however, and these issues are not before this court on
appeal.

                                 -6-
and redhibition.4   After holding that redhibition claims are

limited to economic loss only, the district court granted summary

judgment to Biomatrix on both claims.    The district court

reasoned that without the testimony of Dr. Millet and Dr. Coco,

the plaintiffs had not presented a genuine issue of material fact

tending to show that the injection of Synvisc into plaintiff’s

knee caused his salmonella infection.5   The Pipitones now appeal

the district court’s exclusion of the experts’ testimony, grant

of summary judgment, and holding that redhibition is limited to

economic loss only.

                                 II.

     The plaintiffs first argue that the district court erred in

excluding the testimony of Dr. Millet and Dr. Coco as unreliable

under the standard set forth in Daubert v. Merrell Dow

Pharmaceuticals, Inc..6   We review the district court’s

determination of admissibility of expert evidence under



     4
          Neither party takes issue with this holding, and we do
not consider it.
     5
          Circumstantial evidence may be sufficient under the facts
of a case to establish causation for purposes of liability under
the LPLA. See Joseph v. Bohn Ford, Inc., 

, 940 (La.
1986). The plaintiff need not absolutely negate all other possible
causes of the injury to meet his burden on causation, see 

; rather the plaintiff may prove causation by
establishing “with reasonable certainty that all other alternatives
are impossible.”    Todd v. State, 

, 43 (La. 1997)
(emphasis added).
     6
          

(1993).

                                 -7-
Daubert for abuse of discretion.7

                                  A.

     The Supreme Court’s landmark case of Daubert v. Merrell Dow

Pharmaceuticals, Inc.8 provides the analytical framework for

determining whether expert testimony is admissible under Rule 702

of the Federal Rules of Evidence.9      Under Daubert, Rule 702

charges trial courts to act as “gate-keepers,” making a

“preliminary assessment of whether the reasoning or methodology

underlying the testimony is scientifically valid and of whether

that reasoning or methodology properly can be applied to the

facts in issue.”10   In short, expert testimony is admissible only

if it is both relevant and reliable.11     This gate-keeping



     7
          See Kumho Tire Co. v. Carmichael, 

, 152
(1999); see also St. Martin v. Mobil Exploration & Producing U.S.
Inc., 

, 405 (5th Cir. 2000).
     8
           

(1993).
     9
          

; see also Seatrax, Inc. v. Sonbeck Int’l,
Inc., 

, 371-72 (5th Cir. 2000).
     Rule 702 of the Federal Rules of Evidence provides in full:

     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, if (1)
     the testimony is based upon sufficient facts or data, (2) the
     testimony is the product of reliable principles and methods,
     and (3) the witness has applied the principles and methods
     reliably to the facts of the case.
     10
          

.
     11
          

                                  -8-
obligation applies to all types of expert testimony, not just

scientific testimony.12

     Many factors bear on the inquiry into the reliability of

scientific and other expert testimony.13     In Daubert, the Supreme

Court offered an illustrative, but not an exhaustive, list of

factors that district courts may use in evaluating the

reliability of expert testimony.14     These factors include whether

the expert’s theory or technique: (1) can be or has been tested;

(2) has been subjected to peer review and publication; (3) has a

known or potential rate of error or standards controlling its

operation; and (4) is generally accepted in the relevant

scientific community.15   In the later case of Kumho Tire Co. v.

Carmichael,16 the Supreme Court emphasized that the Daubert

analysis is a “flexible” one, and that “the factors identified in

Daubert may or may not be pertinent in assessing reliability,

depending on the nature of the issue, the expert’s particular

expertise, and the subject of his testimony.”17     The district


     12
          Kumho Tire Co. v. Carmichael, 

, 147 (1999).
     13
          

; Skidmore v. Precision Printing
and Packaging, Inc., 

, 617 (5th Cir. 1999); 

.
     14
          

.
     15
          

see also Moore v. Ashland Chem., Inc., 

, 275 (5th Cir. 1998) (en banc).
     16
          

(1999).
     17
          

                                 -9-
court’s responsibility is “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.”18

     With these guidelines in mind, we turn to the facts in the

present case.   We discuss the district court’s exclusion of the

testimony of plaintiffs’ experts, Dr. Millet and Dr. Coco, in

turn below.

                                B.

     First, plaintiffs argue that the district court abused its

discretion by excluding Dr. Millet’s testimony that Synvisc

caused the salmonella infection in Pipitone’s knee.   Plaintiffs’

primary argument is that the district court erred in excluding

the testimony as unreliable under Daubert.   They point to the

fact that Dr. Millet is an orthopedist who specializes in joints.

He received one year of specialized training in joints at Johns

Hopkins Hospital and has been performing knee injections for

nearly twenty years.

     Assuming, without deciding, that Dr. Millet’s testimony is

sufficiently reliable to meet the Daubert standard, however, we

conclude that his testimony fails the relevancy prong of Daubert

and was properly excluded.   As discussed above, expert testimony


     18
          

                                -10-
is admissible under Daubert only if it is both relevant and

reliable.19   In Daubert, the Supreme Court stated that Rule 702

requires that expert testimony “assist the trier of fact to

understand the evidence or to determine a fact in issue.”20

Thus, to be admissible under Daubert, Dr. Millet’s testimony must

not only be reliable, but also must be relevant to the issue of

causation of the salmonella infection.

     In his deposition testimony, Dr. Millet stated that it was

as likely as not that the Synvisc syringe that he administered to

Pipitone contained the salmonella bacteria that infected

Pipitone’s knee.   He testified that he had no “scientific

evidence” to support the conclusion that it was more likely than

not that the infection occurred in this way.    Dr. Millet then

deferred to Dr. Coco for any other explanation of how the joint

became infected.

     Dr. Millet’s testimony on causation is not helpful to the

fact-finder because of his inability to conclude that it was more

likely than not that the Synvisc caused the infection in

Pipitone’s knee.   A perfectly equivocal opinion does not make any

fact more or less probable and is irrelevant under the Federal

Rules of Evidence.21    Therefore, the district court did not abuse

     19
          

.
     20
          

     21
          See Fed. R. Evid. 401 (“‘Relevant evidence’ means
evidence having any tendency to make the existence of any fact that

                                 -11-
its discretion in excluding Dr. Millet’s testimony.22

                                   C.

     The plaintiffs next attack the district court’s exclusion

under Daubert of Dr. Coco’s testimony that the Synvisc syringe

caused the salmonella infection.         The district court based its

decision to exclude Dr. Coco’s testimony on several factors.

First, after discussing Dr. Coco’s great expertise in the area of

epidemiology and infectious diseases, the district court noted

that Dr. Coco performed no epidemiological study in the instant

case.     The district court also found that Dr. Coco’s literature

search, which yielded no report of any salmonella infection

arising from a contaminated injectable knee product of any kind,

undermined Dr. Coco’s hypothesis that Synvisc caused the

salmonella infection in this case.         Finally, the district court

stated that Dr. Coco had failed to eliminate “many viable

alternative sources” for the salmonella infection.

     The four factors identified in Daubert form the starting

point of the inquiry into the admissibility of expert

testimony.23    However, as the Supreme Court noted in Kumho Tire,


is of consequence to the determination of the action more probable
or less probable than it would be without the evidence.”).
     22
          Of course, this is not to say that Dr. Millet cannot
testify as a lay witness to describe the administration of the
injection, his sterilization procedures, or even his experience
with Synvisc or other injectables. See Fed. R. Evid. 602.
     23
             See Black v. Food Lion, Inc., 

, 311 (5th Cir.
1999).

                                  -12-
“the factors identified in Daubert may or may not be pertinent in

assessing reliability, depending on the nature of the issue, the

expert’s particular expertise, and the subject of his

testimony.”24   It is a fact-specific inquiry.25

     First, Dr. Coco did not test his hypothesis that a Synvisc

syringe that contains salmonella would cause a salmonella

infection in a knee injected with the Synvisc.     Neither side

disputes, however, that if the Synvisc was in fact contaminated,

Pipitone’s knee would probably have been infected.     Dr. Coco did

not conduct an epidemiological study of Pipitone’s infection. He

explained, however, that such a study is not necessary or

appropriate in a case such as this in which only one person is

infected.

     Dr. Coco did conduct a literature search and found no

evidence of a salmonella infection arising from any injectable

knee product, such as Cortisone, which has been injected into

joints for years.    Dr. Coco excluded Synvisc from his search.

The district court found that excluding the defendant’s product

from the search discredited Dr. Coco’s conclusion that the

Synvisc was the source of the salmonella.

     Dr. Coco decided to exclude Synvisc from his search of the

relevant scientific literature primarily because Synvisc is the


     24
            Kumho Tire 

.
     25
            See 

; 

.

                                 -13-
only knee injectable product made from chicken parts, a known

source of salmonella.   By excluding Synvisc, he   sought to

isolate the question he was researching--whether a salmonella

infection had ever arisen from the injection process.    Dr. Coco

reasoned that if Pipitone’s salmonella infection in this case was

caused by unsterile injection technique or some other cause

unrelated to Synvisc, one would reasonably expect to find other

occurrences of salmonella infections arising from injections of

any product into the knee.26

     The lack of literature on injection-related salmonella

infections of the joint does not undermine Dr. Coco’s hypothesis.

As the Supreme Court explained in Kumho Tire, “[i]t might not be

surprising in a particular case, for example, that a claim made

by a scientific witness has never been the subject of peer

review, for the particular application at issue may never

previously have interested any scientist.”27   Where, as here,

there is no evidence that anyone has ever contracted a salmonella

infection from an injection of any kind into the knee, it is

difficult to see why a scientist would study this phenomenon.    We

conclude, therefore, that the lack of reports in the literature

     26
          Neither party contends that Dr. Coco would have found
reports in the scientific literature of a salmonella infection
arising from a Synvisc injection.        In fact, Nancy Larsen,
Biomatrix’s Vice-President of Biomaterials Research, states in her
affidavit that Biomatrix has not received any other report of a
salmonella infection related to Synvisc.
     27
          Kumho Tire 

.

                                -14-
that any knee injectable other than Synvisc has caused a

salmonella infection, supports, rather than contradicts, Dr.

Coco’s conclusion that the infection did not arise due to

unsterile technique or other source not related to Synvisc.

     There is no known or potential rate of error or controlling

standards associated with Dr. Coco’s hypothesis.   Again, however,

this factor is not particularly relevant, where as here, the

expert derives his testimony mainly from first-hand observations

and professional experience in translating these observations

into medical diagnoses.

     The final consideration under Daubert is whether Dr. Coco’s

hypothesis is generally accepted in the relevant scientific

community.   Dr. Coco based his opinion on how Pipitone contracted

salmonella in large part on accepted medical knowledge of the

ways in which salmonella functions as an organism and how it

infects humans.   Dr. Coco’s elimination of various alternative

causes, as discussed more thoroughly below, such as infection

through the gastro-intestinal (“GI”) tract or the blood stream,

were based on generally accepted diagnostic principles related to

these conditions.   Dr. Coco personally examined Pipitone in the

hospital and found him to be lacking the symptoms that a

physician would expect to find if salmonella had been introduced

into the body through one of these alternative routes.

     In a case such as this one, however, it is appropriate for



                                -15-
the trial court to consider factors other than those listed in

Daubert to evaluate the reliability of the expert’s testimony.

In this case, the expert’s testimony is based mainly on his

personal observations, professional experience, education and

training.    The trial court, therefore, must probe into the

reliability of these bases when determining whether the testimony

should be admitted.    The Advisory Committee notes to Rule 702

specifically contemplate this approach:

     Nothing in this amendment is intended to suggest that
     experience alone–or experience in conjunction with other
     knowledge, skill, training or education–may not provide
     sufficient foundation for expert testimony. To the
     contrary, the text of Rule 702 expressly contemplates that
     an expert may be qualified on the basis of experience.28

     Likewise, in Kumho Tire, the Court explained that “no one

denies that an expert might draw a conclusion from a set of

observations based on extensive and specialized experience.”29

Accordingly, this circuit has upheld the admission of expert

testimony where it was based on the expert’s specialized

knowledge, training, experience, and first-hand observation while

supported by solid evidence in the scientific community.30

     28
            Fed. R. Evid. 702 advisory committee’s note.
     29
            Kumho Tire 

.
     30
          See 

(holding that the district
court properly admitted testimony of a psychiatrist who diagnosed
plaintiff because the psychiatrist “testified to his experience, to
the criteria by which he diagnosed [the plaintiff], and to the
standard methods of diagnosis in his field”); St. Martin v. Mobil
Exploration & Producing U.S., Inc., 

, 406-07 (5th Cir.
2000) (holding that ecologist’s first-hand observation of flooded

                                 -16-
     As stated before, Biomatrix does not dispute Dr. Coco’s

opinion that the Synvisc syringe used by Pipitone, if

contaminated with salmonella, would have caused his infection.

Biomatrix takes issue only with Dr. Coco’s finding that, in light

of all of Dr. Coco’s knowledge of and experience with salmonella

and how people do and do not contract it, as well as his

observation of Pipitone, the Synvisc syringe was the source of

the contamination.

     Dr. Coco specializes in infectious diseases.      He is employed

by three local hospitals in the area of hospital epidemiology and

concentrates in this area as it relates to infectious diseases

and the prevention thereof.   He has been on the Specialty Board

of Infectious Diseases and has written on the subject.      For the

last twelve years, Dr. Coco has been a Clinical Assistant

Professor at Louisiana State University School of Medicine in the

Department of Infectious Disease.      Dr. Coco drew on this

experience when he personally examined Pipitone in January 2000.

Based on his experience as an infectious disease specialist and



marsh at issue combined with his expertise in marshland ecology
were sufficiently reliable bases of his opinion on causation under
Daubert to admit the testimony). Compare with Moore v. Ashland
Chem., Inc., 

, 278 (5th Cir. 1998) (holding that the
district court did not abuse its discretion in excluding expert
testimony on the cause of plaintiff’s “RADS” where there was no
evidence that the chemical agent plaintiff was exposed to caused
RADS); Black v. Food Lion, Inc., 

, 312-13 (5th Cir.
1999) (holding that expert testimony should have been excluded
under Daubert where, contrary to the expert’s opinion, there was no
solid medical evidence that trauma could cause fibromyalgia).

                                -17-
his personal observation of Pipitone and his symptoms, Dr. Coco

concluded that the most likely cause of Pipitone’s infection was

the Synvisc that had been injected into his knee two days before.

Specifically, Dr. Coco based this opinion on the timeliness of

the infection (symptoms of which began to appear hours after the

Synvisc injection), the source of the Synvisc, the type of

organism (salmonella) that infected Pipitone, and the elimination

of all other likely alternatives.

     The district court grounded its decision to exclude Dr.

Coco’s testimony on causation largely because it found that Dr.

Coco had identified “many viable alternative sources” of the

salmonella infection in Pipitone’s knee.       After a careful review

of the summary judgment record, we are satisfied that the record

does not support this statement.       Dr. Coco methodically

eliminated the alternative sources of the infection as viable

possibilities.   After doing so, he stated that he was “99.9%”

sure that the source of the salmonella was the Synvisc syringe.

     One of the alternatives rejected by Dr. Coco was that

Pipitone ingested salmonella, the bacteria infected his GI tract

(a condition called gastroenteritis), translocated into his

bloodstream (a condition called bacteremia), and traveled

directly to his knee, causing the infection.       Another alternative

source was that the salmonella infected his scabbed-over toe,

traveled in his bloodstream (also producing bacteremia), and



                                -18-
infected his knee.    Dr. Coco rejected both of these alternatives,

however, on the grounds that Pipitone showed none of the symptoms

associated with either gastroenteritis or bacteremia when Dr.

Coco examined him in the hospital.       Dr. Coco testified that when

he examined Pipitone, Pipitone “did not have diarrhea, nausea, or

vomiting”–-the symptoms of gastroenteritis.      Dr. Coco also

testified that Pipitone was not running a fever at the time of

his entry into the hospital, nor did he have chills or severe

inflammatory response associated with bacteremia.31      Dr. Coco

also noted that it is nearly impossible to contract salmonella

through even an open traumatic wound, much less the scabbed-over

surface of Pipitone’s toe.   Based on the lack of these symptoms

and his specialized knowledge and experience, Dr. Coco ruled out

these alternatives.

     Another possible cause of the salmonella infection that Dr.

Coco rejected as a viable alternative was Dr. Millet’s technique

in administering the injection.     Dr. Coco interviewed Dr. Millet

about the technique he used in giving Pipitone the Synvisc

injection.   Dr. Coco testified that the alcohol and the

antibiotic cleanser that Dr. Millet used to clean Pipitone’s knee

before the injection would have killed any salmonella on the


     31
          Dr. Coco also made clear that the fact that Pipitone was
diabetic and that he was on Zantac only affected his likelihood of
contracting gastroenteritis, not a salmonella infection in any
other way.    These facts made Pipitone no more predisposed to
bacteremia, for example.

                                  -19-
skin.     Dr. Coco further testified that he learned from Dr. Millet

that the injection needle was in a protective sheath until Dr.

Millet injected Pipitone.    Even if the needle had been removed

from the sheath some time before the injection, however, Dr. Coco

stated that salmonella does not exist in sufficient quantities on

the hands to contaminate an injection needle nor does it exist in

saliva in an individual’s mouth.         Dr. Coco testified that if

unsterile injection technique could cause salmonella infection in

a joint, he would have expected to have found reports of such an

occurrence in the literature, regardless of the drug being

injected.     Yet, Dr. Coco’s research revealed no evidence of any

injectable causing a salmonella infection in a knee.         Given all

of this information, Dr. Coco concluded that the content of the

Synvisc syringe injected into Pipitone was the most likely source

of the salmonella that infected his knee.32

     Finally, Biomatrix argues that Dr. Coco’s unfamiliarity with

the Synvisc manufacturing process and his “inability” to explain

the lack of salmonella in the other Synvisc syringes held back

     32
          Dr. Coco rejected a number of other alternatives which we
do not discuss in depth here. For example, he stated that it was
extremely unlikely that salmonella could have entered Pipitone’s
knee through the needle tract, which was open momentarily when the
aspiration syringe was replaced with the Synvisc syringe.        He
testified that he had never seen any report in the medical
literature of a salmonella infection occurring in this way.
Moreover, Dr. Coco stated that this alternative is subject to the
same question presented above; that is, if this was likely, one
would expect there to be some evidence of a salmonella infection
occurring in this manner in the past with the injection of any type
of joint injectable.

                                  -20-
from Pipitone’s production lot renders his testimony “unreliable”

under Daubert.   We disagree with Biomatrix’s characterization of

Dr. Coco’s deposition testimony.       Dr. Coco stated that while he

would have expected other samples of Synvisc in the same

manufacturing lot to be contaminated, the absence of salmonella

in those few other samples tested did not undermine his

conclusion.   Dr. Coco explained that only a small number of

Salmonella organisms would be required to infect a joint that was

directly exposed to the organism.      He also stated that in his

epidemiological experience, a batch that produces a contaminated

sample may contain no other contaminated samples.33      Therefore,

     33
          Dr. Coco based this conclusion on basic epidemiologic
principles and his experience as an epidemiologist for three
hospitals, where he has studied incidents of contamination related
to various batched medicines. Specifically, Dr. Coco testified:

     Q:   I guess in order to understand the contamination of the
          injection, is it in your experience then that if one
          injection is contaminated, others would be as well?

     A:   No, it doesn’t have to be.

     Q:   What’s your experience?

     A:   The experience is, generally, if a specific product is
          batched, the entire batch is suspect.             But in
          epidemiologic surveys, batches of product, generally, not
          all of them are contaminated. Only a small percent of
          them.   No one understands why this occurs.     But, for
          instance, you can have 10,000 recalled of a certain thing
          and only a few be actually contaminated.

     Q:   When you say a few, would you expect more than one in a
          batch?

     A:   It could be–it could be between one and all of them. It
          does not have to be all of them. It doesn’t have to be

                                -21-
we disagree with the defendant’s contention that this testimony

renders Dr. Coco’s testimony unreliable under Daubert.

     Based on the summary judgment record in this case, we

believe that the answer to the critical causation question will

depend on which set of predicate facts the fact-finder believes:

the plaintiffs’ contention that the content of the Synvisc

syringe administered to Pipitone was contaminated or the

defendant’s that it was not.   The Advisory Committee notes to

Rule 702 speak to the precise problem in today’s case:

     When facts are in dispute, experts sometimes reach different
     conclusions based on competing versions of the facts. The
     emphasis in the amendment on “sufficient facts or data” is
     not intended to authorize a trial court to exclude an
     expert’s testimony on the ground that the court believes one
     version of the facts and not the other.34

     It bears reminding that “the trial court’s role as

gatekeeper [under Daubert] is not intended to serve as a

replacement for the adversary system.”35   Rather, as Daubert

makes clear, “[v]igorous cross-examination, presentation of

contrary evidence, and careful instruction on the burden of proof

are the traditional and appropriate means of attacking shaky but




          more than one.

     (R. at 797-98).
     34
          Fed. R. Evid. 702 advisory committee’s note.
     35
          Fed. R. Evid. 702 advisory committee’s note, citing
United States v. 14.38 Acres of Land Situated in Leflore County,
Mississippi, 

, 1078 (5th Cir. 1996).

                                -22-
admissible evidence.”36   Thus, while exercising its role as a

gate-keeper, a trial court must take care not to transform a

Daubert hearing into a trial on the merits.   In this case, we

conclude that the standard of reliability that the district court

applied to Dr. Coco’s testimony was overly stringent.    The fact-

finder is entitled to hear Dr. Coco’s testimony and decide

whether it should accept or reject that testimony after

considering all factors that weigh on credibility, including

whether the predicate facts on which Dr. Coco relied are

accurate.

                                III.

     Biomatrix next argues that even if Dr. Coco’s testimony is

admissible, summary judgment for Biomatrix was still appropriate

because the plaintiffs produced no significant evidence that

Biomatrix deviated from its FDA-approved manufacturing

procedures.   The district court apparently agreed.

     The parties agree that the mantle of FDA approval protects

the manufacturer from liability arising from defective design of

the product–not defective manufacture or construction.    The only

issue we must decide, therefore, is whether plaintiffs have

presented a genuine issue of material fact as to whether

Biomatrix deviated from its FDA-approved procedures in

manufacturing the Synvisc at issue in this case.


     36
            

.

                                 -23-
     According to the affidavit of Nancy Larsen, Vice President

of Biomaterials Research at Biomatrix, “[t]he salmonella organism

simply cannot survive the rigorous sterilization, environmental

control, cleaning and testing procedures attendant to the

manufacture of Synvisc.”   It follows that if the content of

Synvisc syringe with which Pipitone was injected was in fact

infected with salmonella, a fact-finder could find that Biomatrix

deviated from its prescribed procedures.   We conclude, therefore,

that a genuine issue of material fact exists as to whether

Biomatrix deviated from its FDA-approved procedures in

manufacturing the Synvisc syringe at issue.   Therefore, we

reverse the district court’s grant of summary judgment in favor

of Biomatrix on plaintiffs’ defective construction and

redhibition claims.

                                IV.

     Finally, the plaintiffs argue that the district court

incorrectly held that their redhibition claim was limited to

economic loss only.   Specifically, plaintiffs argue that the re-

enactment of the title of the Louisiana Civil Code containing the

redhibition articles impliedly repealed portions of the Louisiana

Products Liability Act (“LPLA”) that had been interpreted to

restrict redhibition to recovery of economic loss only.   In light

of our conclusion that the plaintiffs’ redhibition claim survives

summary judgment, we must now address this issue.   We review this



                                -24-
question of law de novo.37

     Article 2520 of the Louisiana Civil Code provides a cause of

action against manufacturers for breach of “warranty against

redhibitory defects.”38    The Code defines “redhibitory defects”

as those defects that “render[] the thing useless, or its use so

inconvenient that it must be presumed that a buyer would not have

bought the thing had he known of the defect.”39    The remedy for

such a breach of warranty is recission of the contract.40    If the

seller knew of the defect, he could also be liable for damages

and attorney’s fees.41    If the seller is also the manufacturer of

the product, the seller is conclusively presumed to know of the

defect.42

     The LPLA, enacted in 1988, provides that it “establishes the

exclusive theories of liability for manufacturers for damages

caused by their products.”43    The statute defines “damage” by

explicitly excluding amounts recoverable under redhibition for



     37
          See Waco Intern., Inc. v. KHK Scaffolding Houston Inc.,

, 528 (5th Cir. 2002).
     

. Code art. 2520 (West 2001).
     39
            

. Code art. 2545 (West 2001).
     42
          See, eg., Dickerson v. Begnaud Motors, Inc., 

, 540 (La. Ct. App. 1984).
     43
            La. Rev. Stat. Art. 9:2800.52 (West 2001).

                                 -25-
damage to the product and other economic loss.44    Courts have

interpreted the LPLA as preserving redhibition as a cause of

action only to the extent the claimant seeks to recover the value

of the product or other economic loss.45

     In 1993, the Louisiana legislature reenacted the entire

title of the Louisiana Civil Code which includes the redhibition

provisions.   Plaintiffs argue that this re-enactment impliedly

repealed the provisions of the LPLA to the contrary and

resurrected redhibition as a full alternative theory of liability

against a manufacturer.

     We are not persuaded.   Under Louisiana law, there is a

strong presumption against implied repeals.46   Moreover, laws on

the same subject must be interpreted in reference to each

other.47   The 1993 re-enactment of the redhibition articles did

nothing to change the LPLA’s definition of “damage.”    Continuing

to read the redhibition articles in product liability cases as

limited to providing a remedy to recover economic loss harmonizes

the two statutes.   We hold, therefore, that the district court


     44
           See La. Rev. Stat. 9:2800.53(5) (West 2001).
     45
          See, eg., Greiner v. Medical Eng’g. Corp., 

,
206 n.5 (5th Cir. 2001); Monk v. Scott Truck & Tractor, 

, 893 (La. Ct. App. 1993).
     46
          See State v. Piazza, 

, 819 (La. 1992);
Standard Supply & Hardware Co. v. Humphrey Bros., 

, 10
(La. 1946).
     47
           See La. Civ. Code art. 13 (West 2001).

                                -26-
correctly held that the plaintiffs’ redhibition claims are

limited to recovery of economic loss only.

                                 V.

     In conclusion, we hold that the district court properly

excluded the expert testimony of Dr. Millet.   However, we

conclude that the district court abused its discretion by

excluding Dr. Coco’s testimony under the standards set forth in

Daubert.   Having concluded that Dr. Coco’s testimony is

admissible, it follows that summary judgment for Biomatrix on

either plaintiffs’ defective construction or redhibition claim is

inappropriate.   We also conclude that a genuine issue of material

fact exists as to whether Biomatrix deviated from its FDA-

approved procedures in manufacturing the Synvisc syringe at issue

in this case.    Finally, we are persuaded that the district court

properly limited the scope of plaintiffs’ redhibition claims to

economic loss only.

     We therefore reverse the judgment of the district court and

remand the case to that court for further proceedings consistent

with this opinion.



REVERSED AND REMANDED.




                                 -27-