Opinion ID: 4588098
Heading Depth: 2
Heading Rank: 1

Heading: Admission of Dr. Rogers’ Testimony

Text: Murphy-Brown also challenges three aspects of the district court’s decisions regarding Plaintiffs’ expert witness Dr. Shane Rogers: (1) its failure to hold a hearing or otherwise exercise its gatekeeping obligation under Daubert, (2) its decision to allow Dr. Rogers to testify about matters that appear to have been beyond his expertise, and (3) its decision to allow the admission of unreliable testimony that the presence of pig2bac meant that hog odor had been present on Plaintiffs’ property. A brief overview of the relevant record is again in order.
Before trial, Plaintiffs proposed to have Dr. Rogers testify as an expert witness about the environmental impact of Kinlaw Farms’ operations. They obtained permission for Dr. 116 Rogers and his associates to take air, manure, and lagoon samples at Kinlaw Farms. Dr. Rogers’ team also collected physical samples at some of Plaintiffs’ properties. One aspect of Dr. Rogers’ proposed testimony derived from testing samples taken from the exteriors of three Plaintiffs’ homes “for the presence of the genetic sequence known as pig2bac.” J.A. 4104. 14 Dr. Rogers stated that this genetic marker is “unique to pig feces,” and thus its presence identifies “the presence of pig feces” in an environment. J.A. 4104–05. In his view, finding pig2bac on the exterior of a residence indicated that hog feces had been present there, and that the presence of hog feces served as a “physical representation of odor” given that the chemical properties associated with pig feces were well-documented to be odorous. J.A. 4110. In short, Dr. Rogers opined that evidence of pig2bac served as a reliable proxy for evidence of odor. Moreover, he asserted that because “pig feces has to be in relatively high concentrations to facilitate . . . detection” of pig2bac, a detectable presence of pig2bac indicated the presence of comparatively higher levels of pig feces and resulting odor. J.A. 4105. Based on this data, Dr. Rogers opined “within a reasonable degree of scientific certainty, that [Kinlaw Farms had] the ability to cause and the effect of causing a substantial interference with Plaintiffs’ use and enjoyment of their property in the form of significant annoyance and material physical discomfort.” J.A. 4110. 14 Dr. Rogers took samples from Tammy Lloyd’s residence in October 2016; in addition, samples were taken from Joyce McKiver and Delois Lewis’ joint residence in November 2016 and from the McKoy home sometime later. All of the samples contained pig2bac. Samples were not taken from the residences of the remaining Plaintiffs. 117 In other words, Dr. Rogers represented that pig2bac was an objective measure of the presence of hog odor on Plaintiffs’ property. Murphy-Brown moved to exclude Dr. Rogers’ testimony from trial, arguing that he lacked the qualifications to be certified as an odor expert, that he had used flawed methods to collect field samples, and that he lacked the scientific foundation needed to offer his opinion about the existence of a nuisance because of his reliance on the unreliable and unproven proposition that pig2bac could serve as a proxy for hog odor. In support of its motion, Murphy-Brown offered a 66-page declaration from its microbiology expert, Dr. Jennifer Clancy, in which she identified flaws in Dr. Rogers’ sample collection protocols and questioned the validity of his use of pig2bac as a proxy for hog odor. Murphy-Brown requested a hearing to address whether Dr. Rogers was Daubert qualified. The district court denied the motion without a hearing, observing that it “simply [could not] honor” a request for oral argument on the motion and that it had reviewed the parties’ written submissions related to the motion. J.A. 6183. Reiterating that it had “read all [the] materials that [had] been submitted with regard to this issue” that morning, it found Dr. Rogers to be “an expert in environmental engineering, . . . animal waste management engineering and technology[,] and microbiology.” J.A. 6185. The sum total of its explanation for its decision was: that in carrying out its Daubert responsibilities, that [Dr. Rogers’] proposed testimony is both reliable and relevant and that the objections and questions regarding his testimony go to the weight and may be covered on crossexamination except insofar as defendant contends that some questions are being – that he may be asked questions outside of the field of his expertise, and the Court obviously is confronted with that question with every expert witness and there will be questions that will be posed to the witness that 118 defendant will contend do not fit the area of expertise which the Court has found him to be in. J.A. 6185–86. Benefiting from this ruling, Plaintiffs called Dr. Rogers “to talk about odor from industrial hog operations.” J.A. 6194. While his testimony covered a host of topics, of particular relevance to this appeal, Dr. Rogers testified that what humans perceive as “hog odor” is actually “a very large mixture, very complex mixture of chemicals that are in [hog] waste treatment systems. So several hundred volatile organic compounds – hydrogen sulfide gas, ammonia gas, for example – and the particles that might carry them.” J.A. 6194. He described the relationship between his expertise and hog odor as knowing “how those [chemicals] are generated from waste management systems . . . and also how those types of particles and gases might move in the environment” until a person “experience[d] them.” J.A. 6194. In Dr. Rogers’ view, testing for hog odor directly is a subjective and unreliable assessment for two reasons. First, humans experience odor differently and therefore measure and perceive it differently. For this reason, he asserted that self-reports and even measurements taken from an olfactometer were too subjective because they required someone to “smell something and then they make a call on it.” J.A. 7204. Second, he opined that testing for the presence of a particular chemical to confirm the presence of hog odor ran its own risks given that hog odor is a complex chemical compound and no one representative chemical could be tested so as to reliably confirm the presence of hog odor. He explained that “any one of [the chemicals comprising hog odor] is extremely smelly” 119 and if one or more are removed, “it’s not likely to change the odor.” J.A. 6206. Consequently, chemicals known to be sometimes present in hog odor may not be present on a particular occasion despite the presence of something identifiable as hog odor. Given these perceived problems with measuring hog odor directly, Dr. Rogers instead elected to rely on the presence of the DNA sequence pig2bac as a means of objectively—but indirectly—testing for the presence of hog odor. Consistent with the view set out in his expert report, Dr. Rogers explained his basis for using pig2bac as a proxy for odor, the results of his investigation of Plaintiffs’ properties outlined earlier, and his opinion that Kinlaw Farms was operating as a nuisance under North Carolina law. When asked to provide “the one thing” he wanted the jurors to take away from his testimony, he replied that he “brought [them] physical evidence that shows that the feces from this operation is moving out into the neighborhood and is impacting – it is a physical marker that shows this operation is impacting the neighbors.” J.A. 7246–47. Of course, Dr. Rogers did not testify without resistance from Murphy-Brown. He was subject to extensive cross-examination that delved into the novelty of his using pig2bac as a proxy for odor. He was also questioned about his decision not to test for certain odorous chemicals in the air despite the ability to do so, about the lack of data documenting the presence and quantity of pig2bac at each plaintiff’s residence, and about the lack of data concerning pig2bac’s general prevalence in the region considering the number of hog farms in eastern North Carolina. In addition, Murphy-Brown called its counter-expert, Dr. Clancy, to testify about some of the flaws she’d identified in Dr. Rogers’ collection protocols, which she said may have led to contaminated results. 120 Murphy-Brown again challenged the admission of Dr. Rogers’ testimony in its motion for a new trial, and the district court summarily denied the motion.
On appeal, Murphy-Brown reiterates its challenges to the admission of Dr. Rogers’ expert testimony, arguing that (1) the district court abandoned its Daubert gatekeeping function by failing to ensure that Dr. Rogers’ testimony about pig2bac was reliable and relevant, (2) the district court improperly admitted him as an expert to opine on how Kinlaw Farms was an odor nuisance when his background did not qualify him as an odor expert, and (3) the district court abused its discretion in allowing Dr. Rogers to testify about the results of his pig2bac testing because this novel theory failed to satisfy Daubert and Rule 702’s reliability standards. Each of these challenges has merit, and the district court erred in ruling otherwise, just as the majority opinion errs in affirming those decisions. Daubert and Federal Rule of Evidence 702 govern the admissibility of scientific evidence through an expert witness. In short, individuals qualified “by knowledge, skill, expertise, training, or education may testify in the form of an opinion or otherwise if” their opinion is based on “specialized knowledge [that] will help the trier of fact to understand the evidence or determine a fact in issue” and “sufficient facts or data,” “the testimony is the product of reliable principles and methods,” and “the expert has reliably applied the principles and methods to the facts of the case.” Fed. R. Evid. 702. “Implicit in the text of Rule 702 . . . is a district court’s gatekeeping responsibility to ‘ensur[e] that an expert’s testimony both rests on a reliable foundation and is relevant to the task at hand.’” Nease v. Ford Motor Co., 848 F.3d 219, 229 (4th Cir. 2017) (quoting Daubert, 509 U.S. at 597 121 (emphases added)). Reliability focuses on the expert’s knowledge and methodology, while relevance looks to whether the evidence “helps the trier of fact to understand the evidence or to determine a fact in issue.” Id. A court that abandons its gatekeeping function necessarily abuses its discretion in allowing the expert to testify. Id. at 228; see Kumho Tire Co. v. Carmichael, 526 U.S. 137, 149 (1999) (observing that when an expert’s “testimony’s factual basis, data, principles, methods, or their application are called sufficiently into question, . . . the trial judge must determine whether the testimony has a reliable basis in the knowledge and experience of the relevant discipline”).
The record reveals the district court’s abdication of its responsibility under Daubert to serve as a gatekeeper before allowing Dr. Rogers to testify about the results of his pig2bac testing. Even a cursory review of the record demonstrates that the court abandoned this required function. After a passing reference to “its Daubert responsibilities,” the court summarily concluded without analysis or explanation that Dr. Rogers’ “proposed testimony is both reliable and relevant and that the objections and questions regarding his testimony go to the weight and may be covered on cross-examination[.]” J.A. 6185. It rejected Murphy-Brown’s multiple challenges as going to weight, not admissibility, without providing any reason and it failed to mention a single aspect of the proposed testimony that supported its conclusion. Faced with a similarly broad and generic admissibility ruling in Nease, we held that the court had abandoned its gatekeeping function, and the majority opinion offers no justification for reaching a different result in this case. Specifically, in Nease, the district 122 court’s ruling “simply dismissed every argument raised by [the defendant] as going to the weight, not admissibility, of [the expert’s] testimony.” 848 F.3d at 230. So too here. Further, in Nease the district “court did not use Daubert’s guideposts or any other factors to assess the reliability of [the expert’s] testimony, and the court did not make any reliability findings.” Id. Here, the record is equally undeveloped, addressing none of the guideposts or other considerations and making no factual findings. Lastly, in Nease “the district court referred neither to Rule 702 nor to Daubert.” Id. On this front, the record here differs just slightly: the district court gave lip service to “its Daubert responsibilities,” but failed to provide any description of what those responsibilities entailed or any analysis applying them. J.A. 6185. The Nease ruling and those here are substantively similar and equally flawed. In both, the district court abandoned its gatekeeping function of “mak[ing] certain that an expert . . . employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.” Kumho Tire Co., 526 U.S. at 152. The district court’s failure to exercise its gatekeeping function was not cured by Murphy-Brown’s robust cross-examination and introduction of a counter-expert witness’s testimony. As this Court recognized in Nease, cross-examination does not serve as a substitute for the district court’s failure to make the threshold gatekeeping decision as to the reliability and relevance of expert testimony. 848 F.3d at 231. Similarly, MurphyBrown’s counter-expert, Dr. Clancy, challenged Dr. Rogers’ protocols for collecting samples, raising concerns about his testing methods that should have been addressed in determining whether to admit his testimony about the results of his testing before it could 123 be heard by the jury. In sum, the whole point of Daubert’s gatekeeping function is “to protect juries from being swayed by dubious scientific testimony” in the first instance, and that purpose is not served by admitting the untested evidence and relying on the jury to determine its reliability. Id. at 231. To do so is to ignore Daubert, which demands that district courts undertake their gatekeeping function role before expert testimony reaches the jurors’ ears. Id. b. Disconnect Between the Scope of Dr. Rogers’ Testimony and His Expertise The second problem with Dr. Rogers’ testimony occurred because the district court allowed him to testify about a wide range of topics that appear to be outside his expertise without adequately inquiring into his qualifications to do so. Part of the court’s gatekeeping function is to ensure that an expert witness is qualified to testify about each component of his testimony. Cf. Belk, Inc. v. Meyer Corp., U.S., 679 F.3d 146, 162 (4th Cir. 2012) (“In undertaking its role as gatekeeper to ensure that proffered evidence is reliable pursuant to Fed. R. Evid. 702, the district court must decide whether the expert has sufficient specialized knowledge to assist the jurors in deciding the particular issues in the case.”). At Plaintiffs’ request, the district court designated Dr. Rogers as an expert in the fields of environmental engineering, animal waste management engineering and technology, and microbiology. But the court then allowed Dr. Rogers to testify extensively about odors and how humans perceive odors without any factual findings that his fields of expertise qualified him to testify about this broader topic. Instead, the jurors were asked to follow and accept Dr. Rogers’ explanation about why his particular training qualified him to opine about hog odor. Plaintiffs respond to Murphy-Brown’s challenges to Dr. Rogers’ 124 expertise by focusing on the fact that he was not designated as an expert on odor; the majority opinion follows suit, pointing out that Dr. Rogers never purported to be an expert on how humans perceive odor. But these are red herrings, distracting from the substance of Dr. Rogers’ testimony, because he in fact opined at length on these very matters. Dr. Rogers testified about how an industrial hog farm such as Kinlaw Farms generates odors, why testing for pig2bac on Plaintiffs’ residences “proves” that odors also traveled to their properties, and what led to his opinion Kinlaw Farms substantially interfered with the enjoyment of their property. All these representations—and more— necessarily entailed testimony about odors and human perception of hog odors. For example, at the outset of Dr. Rogers’ substantive testimony, Plaintiffs’ counsel quickly transitioned to the observation that “[w]e’re here obviously with the members of the jury to talk about odor from industrial hog operations.” J.A. 6194. Counsel then asked Dr. Rogers a series of questions about how his training and background were relevant to the issue of hog odor’s effect on the environment. He did so by explaining the “way we”— obviously, humans—“perceive a very large mixture, very complex mixture of chemicals” such as “hog odor.” J.A. 6194 (emphases added). Throughout his testimony, Dr. Rogers described the primary sources of odor on a hog farm, and how their design affects odor. He discussed what “particles and gases [in hog operations] have to do with odor” and explained that when “we perceive [something] as odor or whatever, what we’re doing is sensing these different chemicals.” J.A. 6195. And he summarized various studies on why people perceive hog odors with greater “intensity and offensiveness . . . after rainfall or when humidity increases.” J.A. 6917. It’s no surprise, then, that Dr. Rogers agreed that his 125 background made him “an expert” in “whether and how industrial hog odor gets to the neighbors,” which was the issue the jurors would be asked to decide “at the end of the case.” J.A. 6195. Dr. Rogers also testified at length about how hog odor is generated at Kinlaw Farms specifically, basing that testimony on both his knowledge of how industrial hog farms work generally and his site inspection. He labeled particles ventilated from the Kinlaw buildings where the hogs live as “very odiferous” and described at some length for the jury “what’s entering [someone’s] nose” when she “smell[s] hog odor” emanating from those buildings. J.A. 6914. He later provided similar descriptions of how odors transported from the lagoons during storage and decomposition of waste as well as from the spraying of waste onto Kinlaw Farms’ fields. He described “odor tests” he and his team performed on samples from the lagoons to “determine how many dilutions it takes of the material before it no longer has an odor to it,” testifying that it “can take between 800 and even up to nearly 16,000 dilutions before the odors are no longer noticeable” to humans. J.A. 6944, 6957; see also 6954–57. Throughout his testimony, he reiterated that he had experienced the odors he spoke of while at Kinlaw Farms and on Plaintiffs’ property. And he ultimately opined that Kinlaw Farms was “not a good location for this type of a hog operation,” providing additional testimony about various odor-reducing technologies that could be implemented at Kinlaw Farms. J.A. 6985–95. At bottom, notwithstanding Dr. Rogers’ formal designation as an expert in other fields, Plaintiffs presented him to the jury as an expert in odor and human perception of odor, and thus qualified to offer expert opinions on when hog odors create a nuisance. Any 126 assertion to the contrary ignores the substance of his testimony. At a minimum, the district court failed to adequately consider and explain why Dr. Rogers’ background and qualifications were sufficient to permit him to speak about all the aspects of odors touched on in his testimony. And if he was not qualified to testify about these matters, it erred in allowing him to do so. See Fed. R. Evid. 702 (requiring expert’s testimony to be qualified based on “knowledge, skill, experience, training, or education”); Thomas J. Kline, Inc. v. Lorillard, Inc., 878 F.2d 791, 799 (4th Cir. 1989) (observing that although “the test for exclusion is a strict one,” an expert lacking the requisite qualifications should be excluded). Allowing an expert witness to testify outside the areas in which he is qualified leads to the admission of testimony that has the potential to be “both powerful and quite misleading” when it should never have been presented to the jury. Daubert, 509 U.S. at 595. Perhaps Dr. Rogers could have adequately assured the district court of his qualifications to opine on the spectrum of odor-related issues he testified about, but the connection to his qualifications and areas of expertise is not readily apparent in this record. With that in mind, it’s also possible that the discrepancy between Dr. Rogers’ designation and his testimony may not have been sufficient on its own to prejudice Murphy-Brown to such an extent so as to require reversal. But it compounds the district court’s other gatekeeping errs, detailed earlier. The combined effect is error “so fatally infect[ing] the trial” that it violated Murphy-Brown’s substantial rights. Ward, 958 F.3d at 273. c. Unreliability of Dr. Rogers’ Pig2bac Testimony Lastly, the district court’s abdication of its gatekeeping function matters because it led to the improper admission of Dr. Rogers’ unreliable testimony that physical evidence 127 of pig2bac was physical evidence that odors from Kinlaw Farms were traveling to Plaintiffs’ properties. 15 See Bresler v. Wilmington Trust Co., 855 F.3d 178, 195 (4th Cir. 2017) (“In fulfilling its gatekeeping function, a district court must conduct a preliminary assessment to determine whether the methodology underlying the expert witness’ testimony is valid.”). As such, Dr. Rogers’ testimony did not satisfy Daubert or Rule 702, and the court abused its discretion in allowing its admission. In considering the reliability of proposed expert witness testimony, district courts may consider several “guideposts” as well as any other relevant factor. Daubert, 509 U.S. at 593; Nease, 848 F.3d at 229. The guideposts are, first, “whether [a theory or technique] can be (and has been) tested.” Daubert, 509 U.S. at 593. Second, “whether the theory or technique has been subjected to peer review and publication.” Id. Third, “the known or potential rate of error,” as well as “the existence and maintenance of standards controlling the technique’s operation.” Id. at 594. Fourth, whether the theory or technique is generally accepted because “[w]idespread acceptance” hues in favor of admissibility, while “a known technique which has been able to attract only minimal support with the community may properly be viewed with skepticism.” Id. At its core, Daubert’s guideposts are designed to ensure that expert opinion is admitted only when it is reliable, i.e., that it is “based on scientific, technical, or other specialized knowledge and not on belief or 15 Murphy-Brown does not challenge the admissibility of other aspects of Dr. Rogers’ testimony. 128 speculation, and inferences must be derived using scientific or other valid methods.” Oglesby v. Gen. Motors Corp., 190 F.3d 244, 250 (4th Cir. 1999). A foundational concern about Dr. Rogers’ pig2bac testimony is the novelty of its use as a proxy for odor, which was the basis of his testing and for much of his testimony. For example, Dr. Rogers admitted that he was unaware of anyone who used pig2bac as a surrogate for odor in the way he had done for purposes of forming his opinion in this case. J.A. 7221 (Q: “No one ever reports Pig2bac used the way you use it, do they?” A: “Not that I’m aware.”). Further, he admitted that the pig2bac proxy theory and the methodology for detecting “odor” that he used in this case had never been published (by him or anyone else). J.A. 7222. And he acknowledged that no one had suggested in “the peer-reviewed literature” that his approach was “an appropriate scientific method . . . to measure odor leaving the farm.” J.A. 7222. While it is not clear from the record that he developed his method strictly for purposes of this litigation, it is indisputably new—and unique to Dr. Rogers—and does not have any credence in the broader scientific community. See United States v. Crisp, 324 F.3d 261, 268 (4th Cir. 2003) (observing that although Daubert “enabled the courts to entertain new and less conventional forms of expertise” than the prior “uncompromising general acceptance test,” it nonetheless “attempted to ensure that courts screen out junk science”); see also Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1317 (9th Cir. 1995) (observing that a “significant fact to be considered” as part of the Daubert analysis is whether an expert is testifying “about matters growing naturally and directly out of research they have conducted independent of the litigation, or whether they have developed their opinions expressly for purposes of testifying”). Although the 129 novelty of a methodology and theory is not dispositive to the Daubert analysis, it is relevant and prompts giving additional attention to whether other indicia of reliability exist. See Daubert, 509 U.S. at 594; Daubert, 43 F.3d at 1317–18 (observing that “other objective, verifiable evidence that the testimony is based on scientifically valid principles” that have “been subjected to normal scientific scrutiny through peer review and publication” is a means of demonstrating reliability despite novelty of a theory). Working from this blank slate, Dr. Rogers developed what appears to be an unsupported and untested hypothesis and opinion that the existence of pig2bac serves as physical evidence of hog odor also having been present at that location such that Kinlaw Farms “is impacting” the Plaintiffs. J.A. 7247. At bottom, his underlying hypothesis satisfies neither Daubert nor Rule 702 because it lacks reliability. Dr. Rogers’ hypothesis was not based on the belief that pig2bac, by itself, was odorous. Instead, he testified that pig2bac was “associated with odor” because it’s a “segment of DNA that’s in fecal bacteria aldolase so that’s bacteria aldolase that come[s] out of feces of the hog and it’s a particle that is in feces of a hog. So that Pig2bac DNA is a very good indicator of the odor that comes along with that feces of the hog.” J.A. 7200 (emphasis added); see also J.A. 6981 (describing the 100 percent correlation between pig2bac and pig feces). At its core, Dr. Rogers’ testimony about pig2bac requires the assumption that detecting pig2bac is a valid surrogate, or proxy, for detecting hog odor. 16 16 Dr. Rogers was contradictory in his testimony about whether pig2bac had any independent odor, at first stating it “probably” did not smell, and then reversing course that because pig2bac is found in bacteria located in pig feces, and because “[o]ften when I’m (Continued) 130 But Dr. Rogers had not performed—and was unaware of any other—tests demonstrating that pig2bac and hog odor actually traveled together. Although he described how “[g]ases, fecal particles and other things” formed and transported from the farm onto neighboring properties, J.A. 6914, he never explained a basis for believing that pig2bac and odor traveled so coterminously that the presence of pig2bac always served as physical evidence of hog odor. In fact, he had never tested whether pig2bac and hog odor were ever present at the same time, let alone run such testing on Plaintiffs’ properties. Further, Dr. Rogers acknowledged that he had not tested whether pig2bac was present at the same time as any chemical typically associated with hog odor, let alone tested for some combination of the complex chemical compound that would be described as “hog odor.” 17 Nor could he testify to how much pig2bac was present, or what correlation—if any—existed between a certain amount of pig2bac and a certain amount or concentration of hog odor. And, of course, because his testing was limited to the presence or absence of pig2bac, he could not testify to the amount of pig2bac present on the properties or provide any correlation between its presence and any particular level of odor that would assist the jury in determining whether it rose to the level of a nuisance. All in all, the association at the core growing bacteria I can smell them,” pig2bac would have the same odor, although he “couldn’t say” what it would smell like or if that smell resembled hog odor. J.A. 7199. Regardless, his testimony centered on this proxy hypothesis. 17 Dr. Rogers’ testimony that he smelled a strong hog odor while collecting the sample from Tammy Lloyd’s house was anecdotal lay testimony rather than scientific evidence demonstrating the reliability of his core hypothesis about pig2bac for Daubert purposes. 131 of Dr. Rogers’ hypothesis was—at least to date and for purposes of this trial—based on pure conjecture rather than scientifically reliable evidence of an odor nuisance. Other aspects of Dr. Rogers’ pig2bac testimony highlight its speculative nature: Dr. Rogers could not be sure that the pig2bac he recovered originated at Kinlaw Farms or was simply the result of its prevalence throughout the region given the number of hog farms in eastern North Carolina. He admitted he’d done no comparative testing of nearby areas such as Elizabethtown to determine whether pig2bac was commonly detected in field samples. Also, Dr. Rogers was unable to provide data about how far pig2bac could travel, instead offering his “susp[icion]” that it could travel at least half-a-mile and could not travel ten miles. J.A. 7189–90. He was similarly uncertain about how long pig2bac could persist in an environment, noting that he’d tested its presence in soil samples “on the order of days” and that it was his “opinion” that it could last “in the air or on a building or on a car” “on the order of weeks.” J.A. 7190–91. Without any scientific evidence to reliably establish a connection between the presence of pig2bac and the presence of hog odor and without any broader acceptance of this hypothesis in the scientific community, the only proffer for the reliability of Dr. Rogers’ method for detecting odors on Plaintiffs’ properties was his own ipse dixit. That’s neither expert testimony nor a sufficient basis for admissibility. Gen. Elec. Co. v. Joiner, 522 U.S. 136, 146 (1997) (observing that courts should not admit an expert opinion supported only by “the ipse dixit of the expert”); Small v. WellDyne, Inc., 927 F.3d 169, 177 (4th Cir. 2019) (“Without testing, supporting literature in the pertinent field, peer reviewed publications or some basis to assess the level of reliability, expert opinion 132 testimony can easily, but improperly, devolve into nothing more than proclaiming an opinion is true ‘because I say so.’”). While strength as to one of the Daubert factors may overcome a deficiency as to another, the totality in this instance leads to the conclusion that Dr. Rogers’ pig2bac testimony lacks the requisite indicia of reliability to be admissible as opposed to simply being subject to cross-examination to test its weight. The admission of Dr. Rogers’ testimony introduced speculation under the guise of science and expertise. That error strikes at the core of what Daubert and Rule 702 are designed to avoid given that “expert witnesses have the potential to be both powerful and quite misleading.” Westberry, 178 F.3d at 261. Based on how it was described and defended in the record, this evidence should never have reached the jury’s ears. For these reasons, the district court abused its discretion in admitting Dr. Rogers’ testimony about pig2bac. 18