IN THE UNITED STATES COURT OF APPEALS

FOR THE FIFTH CIRCUIT

No. 14-20691

DAVID CARLSON; BETSEY CARLSON, 

 Plaintiffs - Appellants

v.

BIOREMEDI THERAPEUTIC SYSTEMS, INCORPORATED; LIGHT 

EMITTING DESIGNS, INCORPORATED, 

 Defendants - Appellees

Appeal from the United States District Court

for the Southern District of Texas

Before PRADO, SOUTHWICK, and GRAVES, Circuit Judges.

LESLIE H. SOUTHWICK, Circuit Judge:

David Carlson suffered severe injuries soon after being treated with the 

defendants’ product, the ProNeuroLight. He and his wife brought this

products liability suit against the defendants. At trial, the defendants’ only 

witness was a chiropractor who had examined Carlson and had been trained 

to use the ProNeuroLight. We agree with the Carlsons that the district court 

erred in allowing that witness to give expert testimony without first making a 

determination about his qualifications. 

We REVERSE and REMAND.

United States Court of Appeals

Fifth Circuit

FILED

May 16, 2016

Lyle W. Cayce

Clerk

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FACTUAL AND PROCEDURAL BACKGROUND

In 2010, David Carlson began to lose nerve sensation in his feet, a 

diabetic condition known as “peripheral neuropathy.” Carlson visited Dr. 

Lance Durrett, “a chiropractor and alternative medicine specialist” who had 

been promoting a new treatment for “diabetic neuropathy.” Dr. Durrett 

examined Carlson and recommended treatment using the ProNeuroLight 

device. The ProNeuroLight uses infrared light “to heat up the area to increase 

the presence of nitrous oxide, which . . . dilates the vessels to allow more 

circulation to get to the area.”1 Dr. Durrett did not personally perform 

Carlson’s ProNeuroLight treatment; it was performed by a staff member in the 

same treatment facility.

Carlson did not experience complications during treatment, and he was 

not examined before leaving the treatment facility. Within 48 hours, Carlson 

discovered ulcers on the bottom of his heels. Carlson’s diabetic podiatrist 

determined these ulcers were in fact “burn eschar.” Ultimately, Carlson’s 

podiatrist concluded these burns caused a bone infection that required “over a 

year of hospitalization culminating in a below the knee amputation on one leg, 

as well as a heel amputation on the opposite foot.”

The Carlsons brought this suit against both the manufacturer and the 

distributor of the ProNeuroLight device, respectively Light Emitting Designs, 

Incorporated and Bioremedi Therapeutic Systems, Incorporated. The Carlsons 

sought damages on three counts of alleged products liability: (1) design defect; 

(2) manufacturing defect;2 and (3) marketing defect, i.e., a failure to warn. 

 

1 In the defendants’ brief on appeal, they provide a different explanation for how the 

device works: “The whole purpose of the ProNeuro device was to stimulate the nerves to make 

them function again.”

2 During trial, in response to the defendants’ motion for judgment as a matter of law, 

the Carlsons conceded their manufacturing defect claim should be withdrawn. The district 

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Before trial, the Carlsons filed a motion to exclude Dr. Durrett’s medical 

testimony. The district court denied the motion without explanation. Dr. 

Durrett was the defendants’ only witness during the five-day trial. The jury 

returned a unanimous verdict for the defendants. The Carlsons timely 

appealed, challenging only the admission of Dr. Durrett’s expert testimony.

DISCUSSION

The Carlsons contend the district court abused its discretion by allowing 

Dr. Durrett, a chiropractor, to “opine[] on medical matters relating to wound 

care, podiatry, neurology, nephrology and diabetic medicine,” as well as “the 

temperature necessary to cause a burn injury” and “opinions on the 

[ProNeuroLight] device itself.” When asked whether the ProNeuroLight 

caused the injuries to Carlson’s feet, Dr. Durrett testified, “I couldn’t conclude 

the device did it or did not do it.” Later, though, he stated clearer opinions. He 

testified that Carlson’s injuries “look[ed] like diabetic ulcers.” When asked to 

comment on a different witness’s conclusion that the ProNeuroLight did cause 

Carlson’s injuries, Dr. Durrett stated: “There is not enough data to make that 

decision.” Dr. Durrett also testified that the ProNeuroLight could not have 

caused Carlson’s injuries. Indeed, he stated the device was incapable of 

causing burns because, by design, it cannot raise surface temperatures by more 

than two degrees Fahrenheit.

The parties appear to agree the challenged testimony is properly labeled 

expert testimony, instead of lay opinion testimony. Though the defendants 

never designated Dr. Durrett as an expert, it is the content of testimony, not a 

witness’s formal designation as an expert witness, which determines whether 

 

court granted the defendants’ motion on this count alone. The district court allowed the 

Carlsons’ two other claims to proceed.

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Rule 702 applies. See FED. R. EVID. 702. That rule must be used to assess “any 

part of a witness’s opinion that rests on scientific, technical, or specialized 

knowledge . . . .” United States v. Cooks, 589 F.3d 173, 180 (5th Cir. 2009). The 

defendants even referred to “Dr. Durrett’s expert opinions” when responding 

to the Carlsons’ pretrial motion to exclude his medical testimony and then 

described the legal standards a court must use to qualify a witness for expert 

testimony. Thus, we assess the challenged testimony under Rule 702.

We also conclude that the Carlsons preserved their challenge to Dr. 

Durrett’s testimony. Initially, the Carlsons filed a pretrial motion to exclude 

Dr. Durrett’s medical testimony. A “pre-trial objection is sufficient to preserve 

the error for appellate review.” Mathis v. Exxon Corp., 302 F.3d 448, 459 & 

n.16 (5th Cir. 2002) (citing the 2000 amendment to Federal Rule of Evidence

103).3 The Carlsons’ motion to exclude did not cite Rule 702 or the caselaw for 

analyzing admissibility of expert opinions, but it sufficiently put before the 

district court the issue of Dr. Durrett’s qualification to give expert testimony. 

The motion argued Dr. Durrett was not qualified “to provide any manner of 

expert medical testimony”; for support, the Carlsons cited an out-of-circuit 

decision considering the proper scope of a chiropractor’s expert testimony. 

Additionally, the Carlsons preserved the issue by twice objecting at trial when 

Dr. Durrett began to testify about medical causation. A party need not 

repeatedly object to preserve an issue where the district court has already 

denied the initial objection. See Douglas v. Alabama, 380 U.S. 415, 420–23 

(1965).4

 

3 We recently acknowledged conflicting precedent in this circuit. Past opinions have

applied an outdated rule requiring that pretrial objections be renewed at trial to preserve 

error. United States v. Lewis, 796 F.3d 543, 545 n.6 (5th Cir. 2015). “Because Mathis is the 

earliest of the conflicting panel opinions, it controls.” Id.

4 The Carlsons did not move to exclude Dr. Durrett’s testimony about the technical 

capabilities of the ProNeuroLight, and at trial they did not expressly object to his testimony

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Because the issue was preserved for appeal, we review the admission of 

expert testimony for an abuse of discretion. Bocanegra v. Vicmar Servs., Inc., 

320 F.3d 581, 584 (5th Cir. 2003). The ruling will be upheld unless it was 

“manifestly erroneous.” United States v. Valencia, 600 F.3d 389, 423 (5th Cir. 

2010). If we find an abuse of discretion, we still may affirm unless the ruling 

“affected the substantial rights of the complaining party.” Nunez v. Allstate 

Ins. Co., 604 F.3d 840, 844 (5th Cir. 2010).

I. Abuse of Discretion

The gatekeeping function identified in Daubert v. Merrell Dow 

Pharmaceuticals, Inc., 509 U.S. 579 (1993), “imposes a special obligation upon 

a trial judge to ‘ensure that any and all scientific testimony . . . is not only 

relevant, but reliable.’” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 147 

(1999) (quoting Daubert, 509 U.S. at 589). “To trigger a Daubert inquiry, an 

expert’s testimony, or its ‘factual basis, data, principles, methods, or their 

application,’ must be ‘called sufficiently into question.’” Rodriguez v. Riddell 

Sports, Inc., 242 F.3d 567, 581 (5th Cir. 2001) (quoting Kumho, 526 U.S. at 

149).

District courts are to make 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.” Pipitone v. Biomatrix, Inc., 288 F.3d 239, 243–44 (5th Cir. 2002)

(quoting Daubert, 509 U.S. at 592–93). “A party seeking to introduce expert 

testimony must show ‘(1) the testimony is based upon sufficient facts or data, 

 

that the device could only raise surface temperatures by two degrees Fahrenheit. These

alleged errors are not preserved for our review, and the Carlsons do not address whether we 

can or should review for plain error. Regardless, we need not address this testimony because 

we reverse on other grounds. The district court may consider its admissibility on remand if 

challenged once more.

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(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.’” Smith v. Goodyear Tire & Rubber Co., 495 F.3d 224, 227 (5th Cir. 2007)

(quoting FED. R. EVID. 702). 

An expert witness’s testimony should be excluded if the district court 

“finds that the witness is not qualified to testify in a particular field or on a 

given subject.” Wilson v. Woods, 163 F.3d 935, 937 (5th Cir. 1999). That said, 

“Rule 702 does not mandate that an expert be highly qualified in order to 

testify about a given issue. Differences in expertise bear chiefly on the weight 

to be assigned to the testimony by the trier of fact, not its admissibility.” Huss

v. Gayden, 571 F.3d 442, 452 (5th Cir. 2009).

Initially, we dispose of the defendants’ contention that Dr. Durrett gave 

no opinion testimony whatsoever. When asked whether the ProNeuroLight 

could have caused Carlson’s injuries, Dr. Durrett explained there were 

“conflicting facts” and that he could not reach a conclusion. Dr. Durrett’s 

ostensibly equivocal opinion in fact supported the defendants’ case by 

suggesting there was insufficient evidence to prove the ProNeuroLight caused 

Carlson’s injuries.5 Further, Dr. Durrett affirmatively testified that “the 

placement of the [ProNeuroLight] pads couldn’t have” caused Carlson’s 

injuries. This statement alone qualifies as a medical opinion. We thus

consider whether Dr. Durrett’s expert medical testimony was properly 

admitted.

Dr. Durrett has been a practicing chiropractor and alternative medicine 

specialist for over 31 years. He graduated with honors from Texas Chiropractic 

College, has two certifications in acupuncture, and is board certified as a 

 

5 If we agreed that Dr. Durrett provided only “[a] perfectly equivocal opinion,” his 

testimony would be irrelevant and inadmissible. See Pipitone, 288 F.3d at 245.

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chiropractic internist and clinical nutritionist. Dr. Durrett had used devices 

similar to the ProNeuroLight for approximately 14 years at the time he 

testified. Notwithstanding his various professional achievements, Dr. Durrett 

is not a medical doctor, cannot prescribe medicine, did not attend medical 

school, and does not possess a degree from a four-year university. While he 

has considerable experience using the ProNeuroLight, Dr. Durrett’s only 

formal training with the device includes two sales seminars.

A medical degree is not a prerequisite for expert testimony relating to 

medicine. For example, we have held that scientists with PhDs were qualified 

to testify about fields of medicine ancillary to their field of research. See, e.g., 

Dawsey v. Olin Corp., 782 F.2d 1254, 1262–63 (5th Cir. 1986) (holding a 

biochemist who studied the effects of phosgene on animals was “well 

qualified . . . to extrapolate his research to humans”). In the absence of 

expertise in an ancillary field, however, we have held a non-physician is not 

qualified to give medical testimony. See, e.g., Edmonds v. Ill. Cent. Gulf R.R., 

910 F.2d 1284, 1286–87 (5th Cir. 1990). In Edmonds, we noted that the 

witness, a psychologist, was “not a medical doctor, and [was] not involved in 

making medical diagnoses or ordering medical studies or tests,” and so his 

testimony about the medical causation of a patient’s heart disease went 

“beyond this witness’s expertise in the field of psychology.” Id. at 1287.

Unlike the witness in Dawsey, Dr. Durrett does not possess an advanced 

degree in a field of research ancillary to the fields of medicine he testified 

about, such as in podiatry, endocrinology, or nephrology. Further, like in 

Edmonds, Dr. Durrett is not a medical doctor. While he does make diagnoses 

and orders tests as part of his chiropractic and alternative medicine practice, 

Dr. Durrett’s qualifications do not align with or support his challenged medical 

causation testimony. Dr. Durrett may be well-suited to provide expert 

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testimony about the musculoskeletal system,6 yet there is no evidence to 

suggest he is similarly qualified to testify about any other field of medicine.

We need not decide whether Dr. Durrett was qualified to give expert 

testimony, however, because the district court clearly abused its discretion by 

not conducting a Daubert inquiry or making a Daubert determination on the 

record. True, a district court is not always required to hold a formal Daubert 

hearing. See United States v. John, 597 F.3d 263, 274–75 (5th Cir. 2010)

(holding a Daubert hearing is not always necessary “in the context of 

fingerprint evidence”). Nonetheless, we agree with three of our sister circuits

that a district court must still perform its gatekeeping function by performing 

some type of Daubert inquiry and by making findings about the witness’s 

qualifications to give expert testimony. See Smith v. Jenkins, 732 F.3d 51, 64 

(1st Cir. 2013); Naeem v. McKesson Drug Co., 444 F.3d 593, 608 (7th Cir. 2006);

Dodge v. Cotter Corp., 328 F.3d 1212, 1223 (10th Cir. 2003).7 At a minimum, 

a district court must create a record of its Daubert inquiry and “articulate its 

basis for admitting expert testimony . . . .” Rodriguez, 242 F.3d at 581. 

Here, the record reflects that no Daubert inquiry took place. After the 

Carlsons objected to Dr. Durrett’s medical testimony, the district court 

informed the jury: “I find [the testimony] admissible. Whatever weight you give 

to this witness’s testimony, just like every witness, that’s strictly up to you.” 

 

6 Texas’s Occupations Code defines a person practicing chiropractic as one who 

assesses and treats the “musculoskeletal system.” TEX. OCC. CODE § 201.002(b)(1)–(2). We 

do not rely on this definition for our holding, but note it for context. Dr. Durrett’s expert 

qualifications are limited by the absence of any Daubert inquiry or determination

demonstrating he was qualified to testify about medical causation, not by Texas’s 

Occupations Code. 7 These circuits have also reviewed de novo “whether the district court actually 

performed its gatekeeping function in the first place . . . .” See Smith, 732 F.3d at 64; 

Metavante Corp. v. Emigrant Sav. Bank, 619 F.3d 748, 760 (7th Cir. 2010); Dodge, 328 F.3d 

at 1223. We do not decide whether de novo review applies, though, because we find grounds 

for reversal even under the more deferential abuse-of-discretion standard of review.

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With this instruction, the district court disregarded its gatekeeping function to 

determine the admissibility of evidence outside of the presence of the jury. See 

Wellogix, Inc. v. Accenture, L.L.P., 716 F.3d 867, 881 (5th Cir. 2013).

In a similar case from the Seventh Circuit, a prisoner sued the United 

States after a van transporting the prisoner collided with another vehicle. 

Ueland v. United States, 291 F.3d 993, 994 (7th Cir. 2002). The plaintiff’s

“principal ‘medical’ testimony came from . . . a college dropout who claim[ed] 

to be a chiropractor with a practice limited to acupuncture.” Id. at 997. The 

United States challenged this expert’s qualifications to testify about “back and 

neck injuries,” but the district court “refused to apply Rule 702 or conduct a 

Daubert inquiry, ruling instead that [the proposed expert’s] lack of credentials 

and experience concerns only the weight to be accorded to his testimony.” Id. 

The Seventh Circuit disagreed and remanded the case to the district court, 

explaining that “a Daubert inquiry must be conducted.” Id.

We agree with the reasoning in Ueland. An “expert’s testimony must be 

reliable at each and every step or else it is inadmissible.” Knight v. Kirby 

Inland Marine Inc., 482 F.3d 347, 355 (5th Cir. 2007). While Dr. Durrett is an 

experienced chiropractor and alternative medicine specialist, we cannot assess 

on appeal whether he has relevant expertise to support his opinions about 

whether the ProNeuroLight could have, or did, cause Carlson’s foot injuries. 

Admitting this testimony without performing the requisite Daubert inquiry

amounts to an abuse of discretion.

We next consider whether the abuse of discretion affected the Carlsons’ 

substantial rights.

II. Effect on Substantial Rights

Even where a district court abuses its discretion, we will still affirm if 

the error did not affect the substantial rights of the complaining party. We 

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must, though, be “sure, after reviewing the entire record, that the error did not 

influence the jury or had but a very slight effect on its verdict.” Kelly v. Boeing 

Petroleum Servs., Inc., 61 F.3d 350, 361 (5th Cir. 1995).

On the issue of medical causation, the Carlsons presented testimony 

from both Dr. Scott Margolis, Carlson’s treating podiatrist, and Dr. Yadin 

David, a biomedical engineering consultant. When Dr. Margolis was asked 

whether he had an opinion about what caused Carlson’s injuries, he responded, 

“I concluded in my opinion that it was due to the infrared therapy that he was 

undergoing.” Further, Dr. David testified that, with regard to infrared therapy 

devices like the ProNeuroLight, “[t]here are reports of harm, generally burns 

associated with infrared therapy. These reports are particularly worrisome 

because the population purported to benefit from infrared therapy is already 

at a heightened risk for burns due to loss of protective sensation.” 

At the close of the Carlsons’ case-in-chief, the district court denied the 

defendants’ motion for judgment as a matter of law on the design defect and 

failure-to-warn claims. We can infer that at that time, before Dr. Durrett had 

testified, the district court found “that a reasonable jury would . . . have a 

legally sufficient evidentiary basis to find for the” Carlsons. FED. R. CIV. P.

50(a)(1). Dr. Durrett was the sole witness when the defense presented its case. 

Dr. Durrett’s medical causation testimony was also relied upon during the 

defendants’ closing arguments. Defense counsel recounted that Dr. Durrett 

had testified “that he does not believe the device gets hot enough to cause a 

burn,” and that Carlson’s injuries looked like “diabetic ulcers.” 

The jury returned a verdict for the defendants on the Carlsons’ two

remaining counts: (1) finding there was no design defect in the ProNeuroLight;

and (2) finding there was no defect in the marketing of the ProNeuroLight. On 

this record, it is not credible to categorize the admission of Dr. Durrett’s 

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testimony as harmless. Thus, we conclude the district court’s abuse of 

discretion affected the Carlsons’ substantial rights.

* * *

REVERSED and REMANDED for further proceedings.

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