*The Honorable Wiley Y. Daniel, United States District Judge for the District of

Colorado, sitting by designation.

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F I L E D

United States Court of Appeals

Tenth Circuit

DEC 23 1997

PATRICK FISHER

Clerk

PUBLISH

UNITED STATES COURT OF APPEALS

TENTH CIRCUIT

JON BRADLEY SUMMERS; GLYN E.

POTTS,

Plaintiffs - Appellants,

v.

MISSOURI PACIFIC RAILROAD

SYSTEM,

Defendant - Appellee.

No. 96-7038

Appeal from the United States District Court

for the Eastern District of Oklahoma

(D.C. No. CV-94-468-P)

Edward J. Kionka, Carbondale, Illinois, for Plaintiffs - Appellants.

David Lee Crawford, Houston, Texas, for Defendant - Appellee.

Before TACHA, and LUCERO, Circuit Judges, and DANIEL *

, District Judge.

LUCERO, Circuit Judge.
1This provision was formerly part of the Boiler Inspection Act (“BIA”) and was

codified at 45 U.S.C. § 23. The BIA was subsequently repealed and its provisions

recodified. See Act of July 5, 1994, Pub. L. No. 103-272, § 7(b), 108 Stat. 745. The

substance of the BIA remains unchanged by the recodification. See H.R. Rep. 103-180,

at 818 (1994), reprinted in 1994 U.S.C.A.A.N. 818, 818.

2

“Deadheading” is the practice whereby train crews are transported from one

location to another, usually, as in this case, from the place of destination back to their

point of origin or home location. While being transported in this fashion, employees such

as plaintiffs are merely passengers and do not serve as working crew members.

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This action arises under 49 U.S.C. § 207011 and the Federal Employers Liability

Act (“FELA”), 45 U.S.C. §§ 51-60. Plaintiffs Jon Bradley Summers and Glyn E. Potts,

while “deadheading”2 in the service of their employer, defendant Missouri Pacific

Railroad System, allegedly sustained personal injuries which ultimately led to their

claims, trial and a jury verdict for defendant. We are asked to consider whether the

district court abused its discretion in excluding plaintiffs’ expert witnesses and denying

their motion for a new scheduling order, and whether the jury was correctly instructed. 

We exercise jurisdiction pursuant to 28 U.S.C. § 1291. We affirm in part and reverse in

part.

I

In June 1993, while traveling from Oklahoma to Texas in the second engine of a

four-engine locomotive, plaintiffs noticed diesel exhaust in the cab. Summers

complained of a headache, weakness, dizziness, nausea and difficulty breathing, and Potts

experienced a headache, difficulty breathing and tightness in the chest. They notified the

dispatcher, exited the train, and sought medical care. Although treated and released, the
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men continued to experience health problems. Defendant referred plaintiffs to the

Environmental Health Center in Dallas where they were treated by Dr. Alfred Johnson. 

Dr. Johnson’s diagnosis was toxic exposure to diesel fumes resulting in injury to the

central nervous and respiratory systems, causing “chemical sensitivity.” Appellants’ App.

at 455, 522-23. In Dr. Johnson’s opinion, this condition rendered plaintiffs totally and

permanently disabled with respect to railroading and most other types of employment. Id.

at 457-58, 478-79, 482-83.

Thereafter, plaintiffs were referred by defendant to Dr. Thomas Chester, who

concluded that their exposure to diesel exhaust had resulted only in moderate carbon

monoxide poisoning. Id. at 52-53, 63. In his opinion, the effects of such poisoning

dissipate within a few days and, consequently, the incident at issue could not have caused

plaintiffs’ chronic problems. Id. at 54, 58-59, 61. Dr. Chester determined that Potts was

unable to return to work for health-related reasons unrelated to the incident in question. 

With respect to Summers, Dr. Chester thought it possible that he was suffering from

depression, not toxic exposure. Accordingly, he recommended neuropsychological

testing, and for that purpose referred Summers to Dr. Susan Franks. Dr. Franks examined

Summers and, while refusing to diagnose the cause of his condition, found he “was

experiencing a probable dementia that was consistent with a toxic exposure,” id. at 714,

and was “brain-damaged,” id. at 718.
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Prior to trial, defendant filed a motion in limine to exclude the testimony of Drs.

Johnson and Franks. Shortly after the district court granted that motion, plaintiffs filed a

motion for a new scheduling order to procure additional time to obtain alternative medical

testimony. Four days later, plaintiffs were examined by Dr. David Schreiber. Plaintiffs

then submitted Dr. Schreiber’s reports to the district court, as well as railroad retirement

board medical reports prepared by Drs. Thomas Trese and Gordon McWatt. In addition,

they requested that these three doctors be added to the witness list and that the district

court grant them an additional 90 days of discovery. The court denied the motion.

Plaintiffs appeal the district court’s rulings as to both motions. In addition,

plaintiffs contend that the district court improperly instructed the jury on the issue of

causation. 

II

For most of this century, district courts, charged with admitting or excluding

scientific evidence at trial, were guided by the “general acceptance” test set forth in Frye

v. United States, 293 F. 1013, 1014 (D.C. Cir. 1923). The test required excluding such

evidence whenever its underlying scientific principles were not “sufficiently established

to have gained general acceptance in the particular field in which [they belong].” Id. The

Supreme Court has overturned this “dominant standard,” holding that the adoption of the

Federal Rules of Evidence has superseded Frye. Daubert v. Merrell Dow Pharms, Inc.,

509 U.S. 579, 585, 587 (1993). 
3The standard articulated by the Court is simply a restatement of Rule 702, which

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.” Fed. R. Evid. 702. The Court referred to Rule 104(a)

in order to explain that in making this preliminary determination, district courts are not

bound by the rules of evidence except those with respect to privileges, and need only be

persuaded by a preponderance of the proof. See Fed. R. Evid. 104(a); Bourjaily v. United

States, 483 U.S. 171, 175-76 (1987).

-5-

A district court’s decision to admit or exclude expert testimony pursuant to

Daubert is reviewed for abuse of discretion. General Elec. Co. v. Joiner, No. 96-188,

1997 WL 764563, at *7 (U.S. Dec. 15, 1997); see also Compton v. Subaru of America,

Inc., 82 F.3d 1513, 1517 (10th Cir. 1996). We will not disturb the trial court’s

determination “absent a distinct showing it was based on a clearly erroneous finding of

fact or an erroneous conclusion of law or manifests a clear error of judgment.” Cartier v.

Jackson, 59 F.3d 1046, 1048 (10th Cir. 1995).

Under Daubert, when faced with a proffer of expert scientific testimony, a district

court “must determine at the outset, pursuant to [Fed. R. Evid.] 104(a), whether the expert

is proposing to testify to (1) scientific knowledge that (2) will assist the trier of fact to

understand or determine a fact in issue.” Daubert, 509 U.S. at 592.3 When district courts

employ this standard, they ensure the proffered evidence is not only relevant, but reliable. 

See id. at 589. In particular, “scientific knowledge” tests reliability, whereas the second

element, helpfulness to the trier of fact, evaluates relevancy. Reliability is verified by

assessing “whether the reasoning or methodology underlying the testimony is
4Several nondispositive factors should be considered when measuring the

reliability of a particular scientific theory or technique: whether it (1) can be and has been

tested; (2) has been subjected to peer review and publication; (3) has a known or potential

rate of error; and (4) has attained general acceptance in the pertinent scientific

community. See Daubert, 509 U.S. at 593-94; Compton, 82 F.2d at 1518. In considering

these factors, “[t]he focus, of course, must be solely on principles and methodology, not

on the conclusions that they generate.” Daubert, 509 U.S. at 595.

5With respect to assessing relevance, “the district court must determine whether the

methodology or reasoning underlying the expert opinion relates to the issue at hand, i.e.,

whether it assists the trier of fact in understanding the evidence or a fact in issue. In this

regard, the Daubert Court discusses the concept of ‘fitness,’ that is, whether expert

testimony proffered in the case is sufficiently tied to the facts of the case that it will aid

the jury in resolving a factual dispute.” Joiner v. General Elec. Co., 78 F.3d 524, 530

(11th Cir. 1996) (internal quotation and citations omitted).

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scientifically valid.” Id. at 592-93.4 Relevance is determined by ascertaining “whether

[that] reasoning or methodology properly can be applied to the facts in issue.” Id. at 593.5

Plaintiffs were diagnosed by Dr. Johnson as having “chemical sensitivity.” 

Appellants’ App. at 455, 522-23. Defendant concedes that “chemical sensitivity” is a

recognized scientific diagnosis. Id. at 127. Defendant argues, however, that although Dr.

Johnson uses the words “chemical sensitivity,” he is not in fact making that diagnosis, but

is instead applying a scientifically valid label to a scientifically invalid diagnosis of

“multiple chemical sensitivity” (“MCS”). If defendant’s contentions are true, defendant

prevails because MCS is a controversial diagnosis that has been excluded under Daubert

as unsupported by sound scientific reasoning or methodology. See Bradley v. Brown, 42

F.3d 434, 438-39 (7th Cir. 1994); see generally, Kenneth R. Foster & Peter W. Huber,

Judging Science: Scientific Knowledge and the Federal Courts 59 (1997) (“Chemical
6Additionally, the district court noted Dr. Chester’s testimony regarding Dr.

Johnson’s propensity to use varying diagnostic terminology: “[He] take[s] the same

illness, and [he has] used at least three different terms that I know of for that illness . . .

[including] [m]ultiple chemical sensitivit[y], environmental illness and chemical

sensitivity.” Appellants’ App. at 129.

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ecologists have failed to provide criteria that allow a doctor to decide when somebody

does not suffer from MCS which is one of the main reasons why MCS is regarded

skeptically by mainstream medicine.”) Plaintiffs, however, steadfastly maintain that the

doctor’s actual diagnosis is the universally recognized “chemical sensitivity.”

The trial court ultimately concluded that Dr. Johnson’s diagnosis was in fact MCS. 

Thus, the court ruled his testimony inadmissible under Fed. R. Evid. 702 and Daubert. 

The district court’s rationale was that Dr. Johnson performed none of the tests—“a

scratch test, patch test, or a RAST test for IG antibodies”—used to confirm whether or

not a patient is suffering from “chemical sensitivity.” Appellants’ App. at 131. Instead,

Dr. Johnson relied on the patient’s history, a physical examination, and the results of

“Spect” and “Booth” tests. The district court found that these latter tests “have been the

subject of much criticism by the scientific community as not having met acceptable

scientific levels of methodology and criteria, and are not designed to test for the

recognized medical condition of chemical sensitivity.”6

 Id. Plaintiffs do not dispute this

finding, and we therefore may not disturb the court’s conclusion that “the record does not

demonstrate that Dr. Johnson has made a valid diagnosis of the generally accepted

condition of chemical sensitivity based on objective testing.” Id.
-8-

Of course, district courts must be careful not to “don the amateur scientist’s cap in

ruling on scientific validity.” Bradley, 42 F.3d at 438 (citations and quotations omitted). 

But, trial judges remain free to determine as a threshold question whether an expert is in

fact predicating her conclusions on the scientific theory, procedure, or principle on which

she purports to rely. Were this not so, an expert whose opinion rests on faulty scientific

underpinnings might be permitted to testify simply by placing an acceptable label on

otherwise inadmissible “scientific knowledge.”

We also affirm the district court’s exclusion of Dr. Franks’ testimony. The court

found that Dr. Franks, as a psychologist, “is not an expert in the field of medicine or

toxicology,” see Appellants’ App. at 132, and further found that her opinion was based in

part on testing that was still “in the research stage and [had] not been validated,” id. at

133. Plaintiffs provide us with no evidence indicating that the district court’s resolution

of this issue was in error.

III

The district court denied plaintiffs’ motion for a new scheduling order citing the

untimeliness of their request and prejudice to defendant. Federal Rule of Civil Procedure

16(b) provides that schedules “shall not be modified except upon a showing of good

cause and by leave of the district judge . . . .” “Nevertheless, while the pretrial order

defines a lawsuit’s boundaries in the trial court and on appeal, ‘total inflexibility is

undesirable.’” Hull v. Chevron U.S.A., Inc., 812 F.2d 584, 588 (10th Cir. 1987) (citing
7We decline to reach a conclusion as to the propriety of excluding the testimony of

Drs. Trese and McWatt. There is some question as to whether plaintiffs withheld the

names of Drs. Trese and McWatt and their medical reports from the defendant. If this is

determined to be the case, exclusion of testimony is a proper response to the discovery

violations. See Orjias v. Louisiana-Pacific Corp., 31 F.3d 995, 1005 (10th Cir. 1994)

(citing Fed. R. Civ. P. 37(c)). Neither the record nor the district court order clarify the

situation, and thus we do not have sufficiently detailed findings to permit appellate

review. See Krieger v. Gold Bond Bldg. Prods., 863 F.2d 1091, 1097 (2d Cir. 1988). As

to Drs. Trese and McWatt, we therefore vacate the order denying plaintiffs leave to add

them as witnesses, and remand for further proceedings in light of this opinion.

-9-

Fed R. Civ. P. 16 advisory committee’s note). The decision to exclude evidence is a

drastic sanction. See Coleco Indus., Inc. v. Berman, 567 F.2d 569, 576 n.14 (3d Cir.

1977). Because district courts are given wide latitude in this area, we reverse only for

abuse of discretion. See Burks v. Oklahoma Publ’g Co., 81 F.3d 975, 978 (10th Cir.),

cert. denied, 117 S.Ct. 302 (1996). 

Even according appropriate deference, we find reversible error in this case. Our

determination turns on four factors:

(1) the prejudice or surprise in fact of the party against whom the excluded

witnesses would have testified, (2) the ability of that party to cure the prejudice,

(3) the extent to which waiver of the rule against calling unlisted witnesses would

disrupt the orderly and efficient trial of the case or of other cases in court, and (4)

bad faith or willfulness in failing to comply with the court’s order.

Burks, 81 F.3d at 979 (quoting Smith v. Ford Motor Co., 626 F.2d 784, 797 (10th Cir.

1980)).

The first two factors favor granting plaintiffs’ request to modify the scheduling

order and add Dr. Schreiber as a witness.7 Defendant could hardly have been surprised
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that plaintiffs would attempt to procure alternative expert testimony in the event the court

granted defendant’s motion to exclude the testimony of Drs. Johnson and Franks. In fact,

defendant was already prepared to present expert testimony that plaintiffs were not

suffering from chronic medical problems. Moreover, any prejudice to defendant could

have readily been cured; the substance of Dr. Schreiber’s testimony could have been

established through deposition and by review of his reports. 

We cannot conclude that the plaintiffs’ request for a new scheduling order would

have disrupted the trial—their motion was filed eighty days before its scheduled

commencement. Cf. National Distillers and Chem. Corp. v. Brad’s Mach. Prods., Inc.,

666 F.2d 492, 497 (11th Cir. 1982) (finding twenty-one days notice of new witness prior

to commencement of trial sufficient); Davis v. Duplantis, 448 F.2d 918, 921 (5th Cir.

1971) (finding eight days notice of testimony of witness not listed in pretrial order

sufficient). Additionally, the plaintiffs acted promptly to find new experts. The district

court entered the order excluding Drs. Johnson and Franks on August 25, 1995. The

written motion for a new scheduling order was filed on September 15 and on September

19 the plaintiffs were examined by Dr. Schreiber. On October 25, Dr. Schreiber produced

preliminary medical reports for both plaintiffs and on November 1, the date of the hearing

on the motion for a new scheduling order, plaintiffs’ counsel submitted these reports to

the court and opposing counsel. 
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Thus, by the date of the hearing, the plaintiffs were prepared to present not only

the identity of the proposed expert, but his preliminary conclusions as well. The

presentation of Dr. Schreiber’s preliminary reports was sufficient to put everyone

concerned on notice that the subject matter of this proposed testimony would be different

than that of the properly excluded testimony of Dr. Johnson. The reports prepared by Dr.

Schreiber clearly indicate that both plaintiffs suffer from objective abnormalities which,

in the case of Summers, he attributes to “toxic damage to his central and peripheral

nervous system as a result of exposure to the fumes.” Appellant’s App. at 931. Even if

Dr. Schreiber’s testimony were to be excluded on Daubert review, it could not be

excluded for the same reasons relied on to exclude Dr. Johnson’s testimony. The district

court noted that diagnoses of MCS, including that of the plaintiffs, rely on subjective

symptoms “that cannot be attributed to any known condition, disorder, or disease.” Id. at

130 (citation omitted). Dr. Schreiber’s preliminary reports do not indicate such reliance. 

 Our review of the record reveals no bad faith or willful omissions on the part of

plaintiffs. On the contrary, this dispute presents unique facts that demand reversal. 

Plaintiffs were referred to Drs. Johnson and Franks by defendant, their employer. To

deny them the opportunity to acquire new expert witnesses after Johnson and Franks were

excluded is unjust. Their disputed diagnoses were in part a function—albeit

inadvertent—of defendant’s actions. The district court’s order denying the motion for a

new scheduling order states “the plaintiffs were aware, at least as early as the beginning
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of discovery, that defendant had repudiated the testimony and diagnosis of both Drs.

Johnson and Franks.” Appellants’ App. at 142-43. That, however, was insufficient to put

plaintiffs on notice that the testimony of both doctors would be excluded altogether. 

“Zeal to dispose of pending litigation, commendable in itself, [should not result] in

deprivation of reasonable opportunity to make adequate preparation for trial.” Sutherland

Paper Co. v. Grant Paper Box Co., 183 F.2d 926, 931 (3rd Cir. 1950). The plaintiffs

acted expeditiously in filing the motion for a new scheduling order and obtaining

alternative medical testimony. Under these circumstances, the district court’s decision to

deny plaintiffs’ motion without affording plaintiffs an opportunity to develop the

testimony and subject it to further Daubert analysis was improvident. We reverse on that

basis.

IV

We review the district court’s decision to give a particular jury instruction for

abuse of discretion. Harrison v. Eddy Potash, Inc., 112 F.3d 1437, 1442 (10th Cir. 1997). 

The instructions given are reviewed de novo to determine whether, in their entirety, they

correctly state the governing law. Id. “An erroneous jury instruction requires reversal

only if we have substantial doubt whether the instructions, taken together, properly

guided the jury in its deliberations.” Faulkner v. Super Valu Stores, Inc., 3 F.3d 1419,

1424 (10th Cir. 1993) (quotations omitted).
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The district court informed the jury that “for the plaintiffs to recover any damages

under the Boiler Inspection Act [(“BIA”)], they must prove that their injury resulted in

whole or in part from the defendant’s violation of the [BIA].” Appellants’ App. at 181

(emphasis added). Plaintiffs objected to this instruction, suggesting in its place language

stating they were entitled to recover if the violation “played any part, no matter how

small” in causing the injury. Id. at 383-84. On appeal, plaintiffs argue that the district

court’s failure to include the proposed language constitutes reversible error. We disagree.

Actions alleging a violation of the BIA are brought under the FELA. See Urie v.

Thompson, 337 U.S. 163, 188 n.30 (1949). The standard of causation required in a BIA

case is the same as the standard of causation required in a FELA negligence case. See,

e.g., Oglesby v. Southern Pacific Transp. Co., 6 F.3d 603, 606 (9th Cir. 1993); Green v.

River Terminal Ry. Co., 763 F.2d 805, 810 (6th Cir. 1985). Therefore, we are required to

analyze the statutory language of the FELA and the case law interpreting it in order to

determine whether the jury instruction given by the district court was correct as a matter

of law. See Oglesby, 6 F.3d at 606.

The FELA provides:

Every common carrier by railroad . . . shall be liable in damages to

any person suffering injury while he is employed by such carrier . . . for

such injury . . . resulting in whole or in part from the negligence of any of

the officers, agents, or employees of such carrier, or by reason of any defect

or insufficiency, due to its negligence, in its cars, engines, appliances,

machinery, . . . or other equipment.”
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45 U.S.C. § 51 (emphasis added). During the first half of this century, it was customary

for courts to analyze liability under the FELA in terms of proximate causation. See Page

v. St. Louis Southwestern Ry. Co., 312 F.2d 84, 88 & n.2 (5th Cir. 1963) (citing cases). 

However, the Supreme Court definitively abandoned this approach in Rogers v. Missouri

Pacific R.R., 352 U.S. 500 (1957), stating,

Under this statute the test of a jury case is simply whether the proofs

justify with reason the conclusion that employer negligence played any part,

even the slightest, in producing the injury or death for which damages are

sought. It does not matter that, from the evidence, the jury may also with

reason, on grounds of probability, attribute the result to other causes,

including the employee’s contributory negligence. Judicial appraisal of the

proofs to determine whether a jury question is presented is narrowly limited

to the single inquiry whether, with reason, the conclusion may be drawn that

negligence of the employer played any part at all in the injury or death. 

Judges are to fix their sights primarily to make that appraisal and, if that test

is met, are bound to find that a case for the jury is made out whether or not

the evidence allows the jury a choice of other probabilities. The statute

expressly imposes liability upon the employer to pay damages for injury or

death due “in whole or in part” to its negligence.

The law was enacted because the Congress was dissatisfied with the

common-law duty of the master to his servant. The statute supplants that

duty with the far more drastic duty of paying damages for injury or death at

work due in whole or in part to the employer’s negligence. The employer is

stripped of his common-law defenses and for practical purposes the inquiry

in these cases today rarely presents more than the single question whether

negligence of the employer played any part, however small, in the injury or

death which is the subject of the suit.

Id. at 506-08 (quoting 45 U.S.C. § 51) (second and third emphases added).

Following Rogers, several circuits have held that it is reversible error for a district

court to instruct the jury in a FELA case as to causation using traditional common law
-15-

concepts rather than the standard imposed by the statute. See, e.g., Hausrath v. New York

Central R.R., 401 F.2d 634, 636-37 (6th Cir. 1968); Page, 312 F.2d at 92; DeLima v.

Trinidad Corp., 302 F.2d 585, 587-88 (2d Cir. 1962); Hoyt v. Central R.R., 243 F.2d 840,

843 (3d Cir. 1957).

This circuit has only once been presented with the issue. In Iannacito v. Denver &

Rio Grande Western R.R., 380 F.2d 1019 (10th Cir. 1967), the plaintiff argued that

references to “the proximate cause” in jury instructions that also included “in whole or in

part” language were improper. Id. at 1021. Noting the plaintiff had failed to object to the

instruction at trial, this court concluded that “the instructions taken as a whole

understandably and correctly explained to the jury the applicable law.” Id.

The critical distinction between the instant dispute and the decisions cited above is

that the instruction used by the district court in this case contains no proximate causation

language. In fact, the instruction does no more than quote the relevant statutory language

on causation and, therefore, cannot be a misstatement of the law. See Tyree v. New York

Central R.R., 382 F.2d 524, 526-27 (6th Cir. 1967) (noting that jury instruction that

included “in whole or in part” language “could not be subject to complaint inasmuch as it

specifically told the jury exactly what the statute provided”). 

It is true that a recitation of statutory language does not preclude a finding of error. 

See Draeger v. Grand Central, Inc., 504 F.2d 142, 144 (10th Cir. 1974) (reading statute in

instructing jury “has been considered in some instances to be erroneous”) (citing 9
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Charles Alan Wright & Arthur R. Miller, Federal Practice and Procedure § 2556, n.1

(1971)); see also Structural Rubber Prods. Co. v. Park Rubber Co., 749 F.2d 707, 723

(Fed. Cir. 1984) (finding error in instruction that properly stated law but failed to clarify

term not readily understood by jury). The refusal to accept an alternative jury instruction

could still be an abuse of discretion if the one used misled or confused the jury. See

United States v. Voss, 82 F.3d 1521, 1529 (10th Cir.), cert. denied, 117 S.Ct. 226 (1996). 

Appellants argue that the statutory language is misleading because a reasonable jury could

misinterpret the phrase to require a showing of causation greater than the “no matter how

small” standard explicated in Rogers. We do not agree. 

A jury instruction containing both the statutory language and the explanatory

language of Rogers is certainly the clearest articulation of the appropriate causation

standard and presents the preferable approach in the future. See Iannacito, 380 F.2d at

1021. However, the use of the statutory language is not so misleading as to present a

further basis for reversal. See Coray v. Southern Pac. Co., 335 U.S. 520, 524 (1949)

(stating that FELA’s “in whole or in part” language is “simple and direct”); see also

Hausrath, 401 F.2d at 637 (“The phrase ‘resulting in whole or in part’ was obviously

designed to make even more explicit that negligence of an employer did not have to be

the sole cause or ‘the proximate cause’ of the injury in order to justify recovery.”)

(emphasis added); Iannacito, 380 F.2d at 1021.
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We REVERSE the district court’s order denying plaintiffs’ leave to add Dr.

Schreiber to the witness list, VACATE the order denying plaintiffs’ leave to add Drs.

Trese and McWatt to the witness list and REMAND for a new trial in light of this

opinion. We AFFIRM as to all other issues.
No. 96-7038, Summers v. Missouri Pacific Railroad

TACHA, J., dissenting

I concur with Parts II and IV of the majority opinion. With respect to Part III,

which reverses the denial of plaintiffs’ motion to amend the scheduling order, I

respectfully dissent. As this court noted in Burks v. Oklahoma Pub. Co., 81 F.3d 975, 978

(10th Cir.), cert. denied 117 S. Ct. 302 (1996), “Federal Rule of Civil Procedure 16(b)

gives district courts wide latitude in entering scheduling orders.” That rule provides that

“[a] schedule shall not be modified except upon a showing of good cause and by leave of

the district judge.” Fed. R. Civ. P. 16(b) (emphasis added). Because plaintiffs failed to

make a threshold showing of good cause for amending the scheduling order, I would

affirm the district court’s decision on this issue.

When a party seeks an amendment of the scheduling order so that he can substitute

a new expert witness in place of one the court has excluded, that party must put forth

some sort of showing that the proposed witnesses can provide testimony different from

that which already has been rejected by the court as part of the requisite “good cause” for

amending the schedule. Otherwise, the court would be required to constantly amend the

scheduling order to include new substitute witnesses regardless of whether they ultimately

could provide admissible testimony. As the majority discusses in Part II, the district

court here performed a very thorough Daubert analysis regarding the proposed testimony

of plaintiffs’ original medical experts, Drs. Johnson and Franks. As a result of that

analysis, the court decided not to allow their testimony. When plaintiffs moved for a new
-2-

scheduling order to permit Dr. Schreiber to appear as a witness, they made no proffer to

show that his testimony would be different from that already examined and rejected by

the district court. Neither plaintiffs’ written motion nor their attorney’s statements at the

motions hearing purport to explain how Dr. Schreiber’s testimony would differ from that

of the excluded witnesses or how it would meet the Daubert standard. In fact, the

plaintiffs’ attorney said:

Your Honor, I’m not here to tell you that the testimony of Dr. Schreiber will

meet with your requirements and interpretation of Daubert. I don’t know

that. I mean, all we have is a preliminary report . . . .

Hearing Tr. at 12 (Nov. 1, 1995). Perhaps more importantly, an examination of Dr.

Schreiber’s report for plaintiff Jon Bradley Summers reveals no significant difference

between it and the rejected reports of Dr. Johnson. The majority states that “Dr.

Johnson’s diagnosis was toxic exposure to diesel fumes resulting in injury to the central

nervous and respiratory systems, causing ‘chemical sensitivity.’” Majority Op. at Pt. I. 

Dr. Schreiber’s diagnosis for Mr. Summers is very similar. According to Dr. Schreiber’s

report, “it is obvious that Mr. Summers has suffered toxic damage to his central and

peripheral nervous system as a result of the exposure to the fumes while working for the

railroad.” See Appellant’s App. at 931. While he does not go so far as to put a label such

as “chemical sensitivity” on Mr. Summers’ condition as did Dr. Johnson, this omission is

not dispositive. Just as an expert “whose opinion rests on faulty scientific

underpinnings” should not be “permitted to testify simply by placing an acceptable label
-3-

on otherwise inadmissible ‘scientific knowledge,’” Majority Op. at Pt. II, neither should

testimony be admitted simply because the expert declines to give it any label at all. In

short, when they offered Dr. Schreiber’s testimony, plaintiffs did not produce any

additional scientific information that would prompt a need for the district court to conduct

a fresh Daubert analysis for Dr. Schreiber.

Because plaintiffs failed to show that Dr. Schreiber’s testimony would differ in

any significant respect from the testimony the judge had already excluded, they failed to

make a threshold showing of good cause for a change in the scheduling order. Absent

such a showing, it is not necessary for us to address the four factors set out in Burks, 81

F.3d at 979, which the majority analyzes in Part III of its opinion. I would hold that the

trial court did not abuse its discretion when it denied plaintiff’s motion to amend the

scheduling order.