November 01, 2018 Articles

Oh Expert, Where Art Thou?

By Peter A. Meyer and Eldin Hasic

Generally, the threshold issue in a medical device or pharmaceutical drug case is whether the plaintiff has adequate expert evidence to survive a Daubert and summary judgment challenge. If the plaintiff cannot provide adequate expert testimony on the issues of product defect and medical causation, either because plaintiff’s expert cannot survive a Daubert challenge or the plaintiff has not disclosed an expert altogether, the defendant should win the case on a “no evidence” summary judgment motion. Months or years of discovery and case workup often hinge on the presence or absence of this evidence.

As medical devices and pharmaceutical drugs are sold nationally and used more frequently by an aging population, litigation over these products has become omnipresent across all American jurisdictions. This is especially true with the expansion over the last two decades of multidistrict litigations (MDLs), which consolidate hundreds or thousands of federal cases involving the same product before a single judge. The MDL court may end up trying several cases as bellwether trials, each of which could potentially come from, and be governed by the substantive law of, any jurisdiction in the country. For example, Judge Eldon E. Fallon, in the Vioxx MDL venued before him in the Eastern District of Louisiana, tried six bellwethers cases under the laws of five different states: Florida (case tried a second time after mistrial), South Carolina, Kentucky, Utah, and Tennessee. See Eldon E. Fallon et al., Bellwether Trials in Multidistrict Litigation, 82 Tul. L. Rev. 2323, 2335–36 (2008).

Recently, defense counsel (and some judges) have pressed for the adoption of screening orders in MDLs as a means of combating inventories bloated with unmeritorious cases. In ideal circumstances, these screening mechanisms can take the form of a Lone Pine order, requiring individual plaintiffs to present expert evidence that the product at issue was the medical cause of the injuries claimed by each individual plaintiff. In moving for the entry of such an order, or in seeking summary judgment in cases in which plaintiffs fail to comply with such an order, defense counsel may need to cite case law from many different jurisdictions holding that expert testimony is required. We hope the following survey research on expert evidence can serve as an initial reference point for the bar when faced with this scenario, or when litigating individual cases from unfamiliar jurisdictions. Some of the citations provided come directly from state courts, while others are from federal courts applying state law or predicting how the state would decide this issue.

Overall, we find that jurisdictions generally fall into three categories based on the development of their law governing the requirement of expert evidence. First, there are many states, including all the states with large populations, where courts require expert testimony to prove product defect and medical causation in a complex medical device or pharmaceutical drug case. This is the ideal, on-point precedent. The second group consists of states where a court has held that expert testimony is required in cases involving complex, technical issues generally, or in cases involving a different kind of complex product. Making the case that expert evidence is required is usually straightforward in these jurisdictions, because there is usually no question that litigation over the medical device or drug at issue involves some combination of highly technical, scientific, engineering, and/or medical questions outside the common experience and understanding of the jury. In all, our research indicates that 48 states, as well as the District of Colombia and Puerto Rico, fall into one of these first two categories.

That leaves only two states, Alaska and Hawaii, in the third category for which our research did not identify a state or federal court that has reached the issue as precisely. These are both low population states, which may explain the lack of a specific case on the issue. Both Alaska and Hawaii, however, require expert testimony to support complex claims in other areas of law that encompass medical subject matter, namely medical malpractice cases. By analogy, a state that requires expert evidence to prosecute a medical malpractice action before a jury will likely apply the same requirement when faced with a complex, medical product liability case, because the causation issues are similarly complex and outside the common knowledge of a lay juror. Indeed, when squarely faced with this issue, courts in these states would likely find it persuasive that every jurisdiction in the contiguous United States requires expert testimony in medically complex product cases.

Alas, we would not be attorneys if our research did not come with a disclaimer. We make no claim that this is an exhaustive list of cases to cite or that we have found the best or most recent case to cite in each jurisdiction. Rather, this survey is intended to provide a starting point when briefing this issue under the law of an unfamiliar jurisdiction and to illustrate the widespread adoption of this requirement throughout the country.


“[O]rdinarily expert testimony is required because of the complex and technical nature of the commodity.” Hughes v. Stryker Sales Corp., 2010 WL 1961051, at *2 (S.D. Ala. May 13, 2010) (granting summary judgment in a medical device case due to lack of expert testimony of product defect and medical causation and quoting Verchot v. Gen. Motors Corp., 812 So. 2d 296, 303 (Ala. 2001)). The Eleventh Circuit affirmed the Hughes decision and quoted the district court’s explanation that expert testimony on medical causation is required because “the interaction between a complex and technical medical device and the unique physiological and medical circumstances of the patient in which it is implanted is a subject on which no ordinary juror could rationally be expected to have knowledge.” Hughes v. Stryker Corp., 423 F. App’x 878, 881 (11th Cir. 2011).


“While expert testimony is generally required in medical malpractice cases, it is not a general requirement of all professional negligence actions, especially ‘in non-technical situations where negligence is evident to lay people.”’ Johnson & Higgins of Alaska Inc. v. Blomfield, 907 P.2d 1371, 1374 (Alaska 1995) (quoting Kendall v. State, Div. of Corr., 692 P.2d 953, 955 (Alaska 1984)).


Kennedy v. Performance Dodge, L.L.C., 2008 WL 4787630, at *2 (Ariz. Ct. App. Oct. 30, 2008) (“Expert testimony is required when the issues are beyond the common understanding of the jurors.”) (citing Rossell v. Volkswagen of Am., 709 P.2d 517, 524 (Ariz. 1985)); see also Cloud v. Pfizer, Inc., 198 F. Supp. 2d 1118, 1138–39 (D. Ariz. 2001) (excluding plaintiff’s expert’s opinions as unreliable and granting summary judgment in pharmaceutical drug case because “in the absence of [the expert’s] testimony, Plaintiff cannot prove causation.”) and DeSchaaf v. Indus. Comm’n of Ariz., 686 P.2d 1288, 1290 (Ariz. Ct. App. 1984) (holding that “medical causation requires expert medical testimony to establish that the industrial accident caused the injury.”) (internal citations omitted).


Dancy v. Hyster Co. 127 F.3d 649 (8th Cir. 1997) (Arkansas case) (affirming summary judgment for the manufacturer because the operator’s claims required expert testimony of a safer alternative design). The Eighth Circuit explained in Darcy that lay jurors “are not likely to possess common understanding about how products are designed” and thus lay jurors cannot evaluate a proposed alternate design without aid of expert testimony. Id.; see also Nat’l Bank of Commerce v. Assoc. Milk Producers, Inc., 22 F. Supp.2d 942, 949 (E.D. Ark. 1998) (“[A] plaintiff in a toxic tort case must, under Arkansas law, establish medical causation through expert testimony.”) (citing S. Co. v. Graham, 607 S.W.2d 677, 679 (Ark. 1980) and Ambrus v. Russell Chevrolet Co., 937 S.W.2d 183 (Ark. 1997)).


Stephen v. Ford Motor Co., 134 Cal. App. 4th 1363, 1373 (2005) (“Where…the complexity of the causation is beyond common experience, expert testimony is required to establish causation.”); Truman v. Vargas, 275 Cal. App. 2d 976, 982 (1969) (“If the fact sought to be proved is one within the general knowledge of laymen, expert testimony is not required; otherwise the fact can be proved only by the opinions of experts.”); Hickman v. Sofamor-Danek Grp., Inc., 1999 WL 606690, at *7 (N.D. Cal. Feb. 17, 1999) (“To prove causation, [a plaintiff] must present evidence by a competent expert witness testifying to a reasonable degree of medical probability that the [prescription medical device] was a substantial causation factor in plaintiff’s injury.”); Avila v. Willits Envtl. Remediation Tr., 633 F.3d 828, 836 (9th Cir. 2011) (quoting Jones v. Ortho Pharm Corp., 163 Cal. App. 3d 396, 402 (Cal Ct. App. 1985)) (“In California, ‘in a personal injury action causation must be proven within a reasonable medical probability based upon competent expert testimony.”’).


“Colorado provides that ‘expert testimony is required in negligence cases to establish the standard of care when the standard is outside the common knowledge and experience of ordinary persons.”’ Xtreme Coil Drilling Corp. v. Encana Oil & Gas (USA), Inc., 2010 WL 3777303, at *5 (D. Colo. Sept. Sept 19, 2010) (quoting Oliver v. Amity Mut. Irrigation Co., 994 P.2d 495, 497 (Colo. Ct. App. 1999)); see also Truck Ins. Exch. v. MagneTek, Inc., 360 F.3d 1206, 1215–16 (10th Cir. 2004) (affirming summary judgment in a case where expert testimony was needed to prove the cause of a fire and noting that “[j]ury verdicts may not be based on speculation….”).


“If the determination of the standard of care requires knowledge that is beyond the experience of an ordinary fact finder, expert testimony will be required.” Walters v. Howmedica Osteonics Corp., 676 F. Supp. 2d 44, 52 (D. Conn. 2009) (holding that expert testimony was required to assert negligent design claim in a surgical tray case) (citing Santopietro v. City of New Haven, 682 A.2d 106 (Conn. 1996)). Further, “[e]xpert testimony is generally required in cases where the plaintiff alleges that defendant’s conduct caused physical injuries, because the cause of physical injuries is difficult to discern without such expert testimony.” Walters, 676 F. Supp. 2d at 52 (citing Collette v. Collette, 418 A.2d 891, 894 (Conn. 1979) (“[T]he medical effect upon the human system of the infliction of injuries, is generally not within the sphere of the common knowledge of a lay witness....”)); see also Aspiazu v. Orgera, 535 A.2d 338, 342 (Conn. 1987) (holding in a medical malpractice case that “expert testimony is required to establish causation” unless the cause of the “condition is obvious or common in everyday life.”).


Under Delaware law, “[i]f the matter in issue is one within knowledge of experts only and not within the common knowledge of laymen, it is necessary for the plaintiff to introduce expert testimony in order to establish a prima facie [products liability] case.” Reybold Grp., Inc. v. Chemprobe Techs., Inc., 721 A.2d 1267, 1270 (Del. 1998) (emphasis in original) (quoting Money v. Manville Corp. Asbestos Disease Comp. Tr. Fund, 596 A.2d 1372, 1375 (Del. 1991)).

District of Columbia

In Webster, the D.C. federal trial court granted summary judgment in a spinal device case because plaintiffs lacked expert evidence to identify a specific defect or to support medical causation. Webster v. Pacesetter, Inc., 259 F. Supp. 2d 27, 33–34 (D.D.C. 2003). Regarding causation, the court explained that “even if [plaintiffs] could identify a defect, they have failed to proffer evidence from an expert who can testify to a reasonable degree of medical certainty that the defect more likely than not caused the injuries.” Id. at 34. Moreover, the District of Columbia’s general “rule for medically complicated cases is that proof of causation normally requires medical opinion testimony.” Daniels v. District of Columbia, 15 F. Supp. 3d 62, 73 (D.D.C. 2014); see also Arias v. DynCorp, 928 F. Supp. 2d 1, 6 (D.D.C. 2013) (“Expert testimony is not required if the question is not a ‘complex’ one such that the jury can determine causation without the aid of expert testimony based on their own common sense and general experience”); Lasley v. Georgetown Univ., 688 A.2d 1381, 1385 (D.C. 1997) (“To allow a jury of laymen, unskilled in medical science, to attempt to [determine causation without medical opinion testimony in a medically complicated case] would permit the rankest kind of guesswork, speculation and conjecture.”).


“To prove a defective product, a defect must be proven by expert testimony.” Alexander v. Danek Med., Inc., 37 F. Supp. 2d 1346, 1349–50 (M.D. Fla. 1999) (citing Humphreys v. Gen. Motors Corp., 839 F. Supp. 822, 828–29 (N.D. Fla 1993), aff’d, 47 F.3d 430 (11th Cir. 1995)); Payne v. C.R. Bard, Inc., 2014 WL 1887297, at *2 (M.D. Fla. May 12, 2014) (“Expert testimony is generally necessary to prove that a complex product like a medical device is defective.”).


As a practical matter…expert testimony is often required to measure the “gravity and severity of the danger’ posed by a product, the likelihood of that danger, and whether there are feasible alternative designs that would eliminate the danger ‘without impairing the usefulness of the product or making it too expensive.”

Mize v. HJC Corp., 2006 WL 2639477, at *4 (N.D. Ga. Sept. 13, 2006) (quoting Banks v. ICI Americas, Inc., 450 S.E.2d 671, 675 (Ga. 1994)).

See also Brown v. Apollo Indus., Inc., 404 S.E.2d 447, 449 (Ga. Ct. App. 1991) (finding that a lack of expert testimony left the record devoid of evidence of either defectively or negligently designed product); Smith v. Ortho Pharm. Corp., 770 F. Supp. 1561, 1565 (N.D. Ga. 1991) (“Scientific testimony by expert witnesses on the issue of causation plays an increasingly vital role in [Georgia] products liability litigation.”).


Barbee v. Queen’s Med Ctr., 194 P.3d 1098, 1126 (Haw. Ct. App. 2008) (holding in a medical malpractice case the “fundamental requirement of establishing causation by expert medical testimony remains….”) (citing Craft v. Peebles, 893 P.2d 138, 156 (Haw. 1995)); Domingo ex rel. Domingo v. T.K., 289 F.3d 600, 608 (9th Cir. 2002) (“Under Hawaiian law, the plaintiff in a medical malpractice action must show causation through expert testimony”) (case arising out hip implant surgery) (citing Bernard v. Char, 903 P.2d 676, 682 (Haw. Ct. App. 1995) and Devine v. Queen’s Med. Ctr., 574 P.2d 1352, 1353 (Haw. 1978)).


Sabo v. Fiskars Brands, Inc., 2014 WL 4365319, at *16 (D. Idaho Sept. 2, 2014) (“If the complexity of the causation issue is beyond common experience, expert testimony is required to establish causation. An expert’s opinions and conclusions which are based on nothing more than speculation do not constitute substantial evidence.”) (internal citation omitted); Holdaway v. Broulim’s Supermarket, 349 P.3d 1197, 1204 (Idaho 2015) (holding that expert testimony was required in a personal injury case alleging malfunction of an automatic supermarket door because when an “issue is ‘far removed from the usual and ordinary experience of the average person….[a] jury, comprised of lay people, is simply not qualified to determine the issue without the assistance of expert testimony….”’) (quoting Swallow v. Emergency Med. of Idaho, P.A., 67 P.3d 68, 77 (Idaho 2003)); Hansen-Rice, Inc. v. Celotex Corp., 414 F. Supp. 2d 970, 974 (D. Idaho 2006) (under Idaho law, “expert testimony may be required when the facts are beyond the experience of most jurors.”) (citing Jensen v. Am. Suzuki Motor Corp., 35 P.3d 776, 780–81 (Idaho 2001)).


Show v. Ford Motor Co., 697 F. Supp. 2d 975, 987 (N.D. Ill. 2010), aff’d, 659 F.3d 584 (7th Cir. 2011) (“Plaintiffs must present expert testimony to establish a prima facie case of strict liability or negligence.”);

Evidence from a qualified expert is required to resolve these [causation] matters, expert testimony which plaintiff admittedly cannot provide. Without the prospect of expert testimony, plaintiff could not produce at trial evidence to answer or prove these [causation] questions. The trier of fact would have to speculate how to resolve them. It is well-settled that speculation many not be used to manufacture a genuine issue of fact.

Muller v. Synthes, 2002 WL 460827, at *8 (N.D. Ill. Mar. 26, 2002).

See also Fulton v. Theradyne Corp., 2007 WL 772953, at *5 (N.D. Ill. Mar. 12, 2007) (granting summary judgment after finding that “it would be pure speculation if the jury was allowed to assess the design and manufacture of the [product] in the absence of expert testimony”); Niehaus v. United Seating & Mobility, Inc., 2011 WL 5325652, at *3 (S.D. Ill. Nov. 3, 2011) (expert testimony required to establish design and/or manufacturing defect in a wheelchair).


Daub v. Daub, 629 N.E.2d 873, 878 (Ind. Ct. App. 1994) (“When the issue of cause is not within the understanding of a lay person, testimony of an expert witness on the issue is necessary.”); Whitted v. Gen. Motors Corp., 58 F.3d 1200, 1206 (7th Cir. 1995) (“[T]o allow a plaintiff to establish the existence of a design defect by his mere assertion is ludicrous.”) (construing Indiana law); Minisan v. Danek Med., Inc., 79 F. Supp. 2d 970, 975 (N.D. Ind. 1999) (“Proof of legal causation in a medical device case must be by expert testimony and the expert’s opinion must be stated in terms of reasonable probability.”); Menges v. Depuy Motech, Inc., 61 F. Supp. 2d 817, 824 (N.D. Ind. 1999) (same).


Benedict v. Zimmer, Inc., 405 F. Supp. 2d 1026, 1033 (N.D. Iowa 2005) (requiring expert evidence of defect in case involving artificial hip implant); James v. Swiss Valley AG Serv., 449 N.W.2d 886, 890 (Iowa Ct. App. 1989) (“When technical issues are involved (issues beyond common knowledge and experience) in a products liability or a products-related case, expert testimony is required to generate a jury issue.”).


Under Kansas law “expert testimony is required” when the “subject matter is too complex to fall within the common knowledge of the jury and is beyond the capability of a lay person to decide.” Ho v. Michelin N. Am., Inc., 520 F. App’x 658, 667 (10th Cir. 2013) (Kansas case) (expert testimony required to prove defect in truck tire case). Additionally, Kansas federal courts have required expert testimony on causation in a pharmaceutical drug case and on product defect in a medical device case. See Miller v. Pfizer, Inc. (Roerig Division), 196 F. Supp. 2d 1095, 1125 (D. Kan. 2002) (requiring expert testimony on medical causation on failure to warn claim in pharmaceutical drug case because suicide could occur in the absence of use of the product so plaintiffs could not “meet their burden of proof without medical expert testimony that [the drug] more likely than not caused [decedent’s] suicide.”); Ralston v. Smith & Nephew Richards, Inc., 275 F.3d 965, 974–75 (10th Cir. 2001) (Kansas case) (affirming grant of summary judgment on a failure to warn claim in a Kansas knee implant case due to lack of admissible expert testimony.).


Perock v. Medi-Tech, Inc., 2009 WL 982563, at *2 (E.D. Ky. Apr. 10, 2009) (“It is well-established that where a plaintiff claims that a complex medical device is defective, and that the defect was a substantial factor in causing the alleged injury, the plaintiff must come forward with expert testimony to support her claim.”); Burgett v. Troy-Bilt LLC, 970 F. Supp. 2d 676, 681 (E.D. Ky. 2013) (quoting Templeton v. Wal-Mart Stores East, LP, 2011 WL 4591937, at *3 (E.D. Ky. Sept. 30, 2011) (“Under Kentucky law, a plaintiff needs expert testimony when his design defect claim turns on scientific or specialized knowledge that ‘cannot be determined intelligently from testimony on the basis of ordinary knowledge gained in the ordinary affairs of life.”’).


Chavers v. Travis, 902 So. 2d 389, 395 (La. Ct. App. 2005) (“[E]xpert medical testimony is required when the conclusion regarding medical causation is one that is not within common knowledge.”); Hebert v. Miles Pharms., 1994 WL 10184, at *3 (E.D. La. Jan. 13, 1994) (expert testimony required where device involves “complex issues of medical causation, not within the realm of knowledge and experience of the ordinary juror”); Lassiegne v. Taco Bell Corp., 202 F. Supp. 2d 512, 524 (E.D. La. 2002) (citing Pfiffner v. Correa, 643 So. 2d 1228, 1234–35 (La. 1994)) (“The Louisiana Supreme Court has held that when the conclusion regarding medical causation is not one within common knowledge, expert medical testimony is required to prove causation.”); Hutchinson v. Shah, 648 So. 2d 451, 452 (La. Ct. App. 1994) (“When conclusion regarding medical causation is not within common knowledge, expert medical testimony is required.”).


In Doe v. Solvay Pharms. Inc., the District of Maine granted summary judgment on all claims because plaintiff lacked expert testimony to support her liability theory, with the court explaining in the section on design and manufacturing defect claims that “[t]he Achilles’ heel in Ms. Doe’s argument is the absence of any expert testimony on the issues of defect and causation.” See Doe v. Solvay Pharms. Inc., 350 F. Supp. 2d 257, 265 (D. Me. 2004), aff’d, 153 F. App’x 1 (1st Cir. 2005). The court further noted “her treating psychiatrist, who is her only expert, testified that he has no reason to believe that [the drug] she took was negligently manufactured, much less that there was a manufacturing defect that caused her difficulties in 1998,” leaving the court “with a number of critical unanswered questions.” Id. (further noting that Maine courts have generally taken this approach in medically complex cases, such as medical malpractice cases.); see also Kalis v. Strang, 2005 WL 2715239, at *3 (Me. Super. Ct. May 9, 2005)

In the limited medical information that has been provided, there is evidence of prior existing conditions that make it necessary for [the plaintiff] to have a medical expert to opine as to the cause of the claimed injuries. This is not a situation where the injury is so obvious that a lay jury or any person without medical training can identify an injury.

(citing Merriam v. Wagner, 757 A.2d 778, 782 (Me. 2000).

“Allowing a jury to infer causation on complex medical facts without the aid of expert testimony on the subject and without showing that the conduct was more likely than not a cause of the injury, stretches the jury’s role beyond its capacity.” Id. (internal citation omitted).


Cooper v. Smith & Nephew, Inc., 2000 WL 1728024, at *3 (D. Md. Nov. 20, 2000), aff’d, 259 F.3d 194 (4th Cir. 2001) (holding in a spinal fixation medical device case that all of [plaintiff’s] claims require expert medical testimony and granting summary judgment where only evidence of a defect in the device was “conclusory,” “cursory” and based only on inferences); Fitzgerald v. Smith & Nephew Richards, Inc., 1999 WL 1489199, at *2 (D. Md. Dec. 30, 1999) (holding that plaintiff “must rely upon expert testimony” to prove medical causation in a product defect case.).


“As is well-established under Massachusetts law, ‘expert testimony is required to establish medical causation.”’ Milward v. Rust-Oleum Corp., 820 F.3d 469, 476 (1st Cir. 2016) (quoting Reckis v. Johnson & Johnson, 28 N.E.3d 445, 461 (Mass. 2015)); see also Lally v. Volkswagen Aktiengelleschaft, 698 N.E.2d 28, 36 (Mass. Ct. App. 1998) (“[O]ur appellate courts and those in other jurisdictions have recognized the necessity for expert medical testimony on highly technical medical issues….”); Held v. Bail, 547 N.E.2d 336, 338 (Mass. 1989) (holding that when “the causation question involves questions of medical science or technology, the jury requires the assistance of expert testimony.”).


“Expert testimony generally is required to demonstrate a design defect.” Peak v. Kubota Tractor Corp., 924 F. Supp. 2d 822, 831 (E.D. Mich. 2013) (citing Owens v. Allis-Chalmers Corp., 326 N.W.2d 372, 379 (Mich. 1982); Yanovich v. Zimmer Austin, Inc., 255 F. App’x 957, 958 (6th Cir. 2007) (applying Michigan law) (affirming district court’s grant of summary judgment in a knee implant case where plaintiff failed to submit expert medical testimony on the issue of causation and the expert testimony plaintiff did proffer did not sufficiently allege a defect.).


In re Baycol Prods. Litig., 321 F. Supp. 2d 1118, 1126 (D. Minn. 2004) (“[T]his Court joins with those courts that have held personal injury cases involving pharmaceuticals, toxins or medical devices involve complex questions of medical causation beyond the understanding of a lay person.”); Mozes v. Medtronic, Inc., 14 F. Supp. 2d 1124, 1128 (D. Minn. 1998) (holding that expert testimony was “required [for plaintiff] to prove his defective product claims” because “the standard and rationale that Minnesota courts use for determining when expert testimony is required in negligence cases applies fully to products cases.”) (citing Atwater Creamery Co. v. W. Nat’l Mut. Ins. Co., 366 N.W.2d 271, 279 (Minn. 1985)).


Under Mississippi law, experts are necessary when an issue is “wholly beyond the range of the experience or observation of laymen and of which they can have no appreciable knowledge….” Aetna Life Ins. Co. v. Evins, 199 So. 2d 238, 242 (Miss. 1967); see also Harris v. Stryker Spine, 39 F. Supp. 3d 846, 850 (S.D. Miss. 2014) (holding in an orthopedic device case that “expert testimony is generally required” for a plaintiff “to sustain his [or her] burden to prove that a product was defective and that such defect caused the plaintiff’s injury”); Hammond v. Coleman Co., 61 F. Supp. 2d 533, 542 (S.D. Miss. 1999), aff’d, 209 F. 3d 718 (5th Cir. 2000) (granting summary judgment because plaintiff “offered no expert testimony relating to manufacturing defects, design defects, or warning or instruction defects, which precludes recovery on those allegations.”); Wyeth Labs., Inc. v. Fortenberry, 530 So. 2d 688, 692 (Miss. 1988) (holding in a drug case when the alleged warning defect “is not obvious to the ordinary person it is necessary to have expert testimony.”).


In Redd v. DePuy Orthopaedics, Inc., the Eight Circuit affirmed summary judgment in a medical device case because “the cause of sophisticated injuries” must be proven with expert testimony: “Since the fracture of [plaintiff’s] hip stem implant was a sophisticated injury, and [plaintiff] lacked any admissible expert testimony on the cause of that fracture, the district court did not err by granting DePuy summary judgment on her manufacturing defect claim.” Redd v. DePuy Orthopaedics, Inc., 700 F. App’x 551, 555 (8th Cir. 2017) (applying Missouri law); see also v. Missouri-Illinois Tractor & Equip. Co., 711 S.W.2d 935, 937–39 (Mo. Ct. App. 1986) (expert testimony required to prove defect in a front-end coal loader because the engineering and physics issues were outside common knowledge of jury); Davidson v. Besser Co., 70 F. Supp. 2d 1020, 1023 (E.D. Mo. 1999) (whether interlock safety device contained defect was an issue outside common knowledge of jury and expert testimony required to establish liability). “Without expert testimony,” the jury is left “with evidence of an accident [but the] fact that an accident happened, standing alone, does not establish a case of product defect.” Shaffer v. Amada Am., Inc., 335 F. Supp. 2d 992, 998 (E.D. Mo. 2003), aff’d, 2003 WL 26129823 (8th Cir. Sept. 18, 2003).


Because the standards of care applicable in a negligence action against a professional or one involved in a skilled trade are outside the common experience and knowledge of lay jurors, Montana law recognizes that expert testimony is required to establish the standard of care. This requirement has been extended to negligence actions against medical doctors, dentists, orthodontists, veterinarians, lawyers, manufacturers of pharmaceuticals, abstractors of title, and professional counselors.

Wilderness Dev., LLC v. Hash, 606 F. Supp. 2d 1275, 1280–81 (D. Mont. 2009) (emphasis added).

More specifically, the Montana Supreme Court noted that there were “numerous Montana decisions to the effect that, in a malpractice suit against a doctor or dentist, expert evidence is the only proper guide and without a plaintiff cannot recover” and held that the “reasoning of these decisions extends to [pharmaceutical drug cases.]” Hill v. Squibb & Sons, E.R., 592 P.2d 1383, 1388 (Mont. 1979). The court explained that “[b]y logical extension, then, since the warning [in a drug case] is directed to physicians, only they or someone with similar expertise concerning pharmaceuticals would be qualified to determine whether or not the warning was adequate.” Id.; see also, e.g., Estate of Wilson v. Addison, 258 P.3d 410, 415 (Mont. 2011) (“It is well settled Montana law that the plaintiff in a medical malpractice action must establish” the elements of the claim with expert testimony.) (internal citations omitted).


[L]ack of expert testimony on the question of causation results in an insufficiency of proof where the issue involves technical, scientific or medical matters…. Where the exact nature and probable genesis of a particular type of injury involves complicated medical questions far removed from the ordinary experience and knowledge of laymen, only an expert can give competent opinion evidence as to the cause of the injury.

Uribe v. Sofamor, S.N.C., 1999 WL 1129703, *7 (D. Neb. Aug. 16, 1999).

See also Doe v. Zedek, 587 N.W.2d 885, 891 (Neb. 1999) (same); White v. Howmedica, Inc., 490 F.3d 1014, 1016 (8th Cir. 2007) (applying Nebraska law) (affirming “district court’s conclusion that ‘the presence of a defect in an artificial knee component…is not something that is so generally recognizable as to qualify under the so-called common knowledge exception or to eliminate the need for expert testimony.”’).


“To establish causation, a plaintiff must produce medical expert testimony opining to a reasonable degree of medical certainty that the allegedly defective product caused the plaintiff’s injury.” Neal-Lomax v. Las Vegas Metro. Police Dep’t, 574 F. Supp. 2d 1193, 1198 (D. Nev. 2008), aff’d, 371 F. App’x 752 (9th Cir. 2010). Such expert testimony is required “because ‘if the plaintiff’s medical expert cannot form an opinion with sufficient certainty so as to make a medical judgment, there is nothing on the record with which a jury can make a decision with sufficient certainty so as to make a legal judgment.”’ Id. (quoting Morsciato v. Sav-On Drug Stores, Inc., 111 P.3d 1112, 1116 (Nev. 2005)); see also Cabrera v. Cordis Corp., 134 F.3d 1418, 1423 (9th Cir 1998) (affirming District of Nevada’s exclusion of experts under Daubert and grant of summary judgment in medical device case and explaining that “without the experts, [plaintiff] could not prove causation or liability.”).

New Hampshire

“To determine whether expert testimony is required, we must determine whether th[e] issue…is ‘within the realm of common knowledge and everyday experience of the average layman’ or whether an expert opinion is needed to ‘preclude the jury from engaging in idle speculation.”’ Stachulski v. Apple New England, LLC, 191 A.3d 1231, 1241 (N.H. 2018) (food product case) (quoting Laramie v. Stone, 999 A.2d 262, 269 (N.H. 2010) and Estate of Joshua T. v. State, 840 A.2d 768, 772 (N.H. 2003)). Under New Hampshire law, “[l]ay testimony is probative on the issue of physical injury and the cause of that injury only if the cause and effect are so immediate, direct and natural to common experience as to obviate any need for an expert medical opinion” and expert testimony therefore is required “if any inference of the requisite causal link must depend on observation and analysis outside the common experience of jurors.” Reed v. Cty. of Hillsborough, 813 A.2d 472, 473 (N.H. 2002); see also Goudreault v. Kleeman, 965 A.2d 1040, 1048 (N.H. 2009) (“Expert witness testimony is required to establish a prima facie medical negligence case.”); Appeal of Briggs, 645 A.2d 655, 6259 (N.H. 1994) (“The medical causation of a knee injury of this nature is a matter properly within the province of medical experts, and the board was required to base its findings on this issue upon the medical evidence rather than solely upon its own lay opinion.”).

New Jersey

“Expert testimony is generally needed as proof of an alternative warning and a reasonable alternative design to help the fact-finder understand the mechanical intricacies of the instrumentality.” Ebenhoech v. Koppers Indus., Inc., 239 F. Supp. 2d 455, 468 (D.N.J. 2002); see also In re Accutane Litig., 191 A.3d 560 (N.J. 2018) (reinstating trial court’s exclusion of plaintiffs’ experts, which had resulted in dismissal of over 2000 cases with prejudice due to lack of expert testimony); Thompson v. Merrell Dow Pharm., Inc., 551 A.2d 177 (N.J. Super. App. Div. 1988) (affirming summary judgment in case alleging pharmaceutical drug caused birth defect because expert testimony was required and (1) plaintiff’s expert was unqualified to opine on causation and (2) plaintiff’s attempts to rely on expert depositions and experts from other cases involving the same drug were likewise inadmissible);

In performing a risk-utility analysis, an expert opinion is ordinarily relied upon to establish a reasonable alternative design. Expert testimony is required when the subject matter to be dealt with “is so esoteric that jurors of common judgment and experience cannot form a valid judgment as to whether the conduct of the party was reasonable.”

Rocco v. New Jersey Transit Rail Operations, Inc., 749 A.2d 868, 879 (N.J. Super. Ct. App. Div. 2000) (quoting Butler v. Acme Markets, Inc., 445 A.2d 1141, 1147 (N.J. 1982));

Tormenia v. First Investors Realty Co., 251 F.3d 128, 132 (3rd Cir. 2000) (“New Jersey law does require expert testimony, however, in cases where lay jurors confront causation issues that are too complex to be understood without the assistance of specialized expert testimony.”) (citing Kelly v. Borwegen, 230 A.2d 532, 534 (N.J. 1967) (requiring expert testimony on medical causation of injuries such as difficulty sleeping, walking, and climbing stairs allegedly arising out of a car accident)).

New Mexico

Am. Mech. Sols., L.L.C. v. Northland Process Piping, Inc., 184 F. Supp. 3d 1030, 1061 (D.N.M. 2016) (“In general, New Mexico, along with other jurisdictions, has required expert testimony when the issue of causation is presented in a context which is not a matter of common knowledge.”); Duke v. Garcia, 2014 WL 1333151, at *3 (D.N.M. Feb. 28, 2014) (“At minimum, the medical situation is complex, and actions involving medically complicated injuries require expert testimony on causation”) (internal citation omitted). Thus, the Tenth Circuit in a case involving a drug taken in conjunction with a kidney transplant affirmed grant of summary judgment because plaintiff lacked expert testimony on causation: “without her experts’ testimony, [plaintiff] could not show that more likely than not, the tacrolimus suspension dispensed was subpotent, that it was a but-for-case of [plaintiff’s] kidney rejection, or that it was a proximate cause of [her] kidney rejection.” Huerta v. BioScrip Pharm. Servs., Inc., 429 F. App’x 768, 782 (10th Cir. 2011) (applying New Mexico law).

New York

Maxwell v. Howmedica Osteonics Corp., 713 F. Supp. 2d 84, 91 (N.D.N.Y. 2010) (“Generally, under New York law, a plaintiff seeking to establish a design defect is required to provide expert testimony….”); Prohaska v. Sofamor, S.N.C., 138 F. Supp. 2d 422, 445 (W.D.N.Y. 2001) (“Absent competent medical testimony on the issue of causation, plaintiffs cannot prove the elements of a cause of action based in strict products liability or negligence.”); Donovan v. Centerpulse Spine Tech Inc., 416 F. App’x 104, 106 (2nd Cir. 2011) (New York case) (“expert medical opinion evidence…is required, when the subject matter to be inquired about is presumed not to be within common knowledge and experience.”).

North Carolina

North Carolina federal courts have held in medical device cases that “where the injury is complicated, such as a back injury, expert medical testimony on the issue of causation must be provided to support a jury award.” Driggers v. Sofamor, S.N.C., 44 F. Supp. 2d 760, 765 (M.D.N.C. 1998). Thus, in “prior similar cases to this [spinal device case], the Western and Eastern Districts of North Carolina have granted summary judgment based on the plaintiff’s inability to present expert testimony on the issue of causation.” Id. (citing Kirkman v. Sofamor, S.N.C., 1998 WL 666706 (W.D.N.C. July 21, 1998) and Hensley v. Danek Medical, Inc., 32 F. Supp. 2d 345 (W.D.N.C. 1998)).

North Dakota

“As a general rule, a plaintiff is required to prove a product defect through an expert witness.” Burgad v. Jack L. Marcus, Inc., 345 F. Supp. 2d 1036, 1041 (D.N.D. 2004); see also Erling v. Am. Allsafe Co., 230 F.3d 1362 (8th Cir. 2000) (upholding summary judgment on negligent failure to warn, negligent design, and strict liability claims because of lack of expert testimony under North Dakota law). Furthermore, the North Dakota Supreme Court has noted that: “As is usually the case in products liability actions involving technical, scientific, or complex matters, expert opinion was offered on the question on whether the [product at issue was] unreasonably defective and dangerous.” Endresen v. Scheels Hardware & Sports Shop, Inc., 560 N.W.2d 225, 229 (N.D. 1997) (internal citations omitted).


Under Ohio law, a plaintiff must present expert medical testimony to establish causation when she asserts a specific physical injury, the cause of which is not within common knowledge. To prove proximate causation for medical conditions or illnesses allegedly caused by a defective product, a plaintiff must show by a reasonable degree of medical certainty that the disease or injury was caused by the defective product.

Botnick v. Zimmer, Inc., 484 F. Supp. 2d 715, 723 (N.D. Ohio 2007) (citing Conde v. Velsicol Chem. Corp., 24 F.3d 809 (6th Cir. 1994), Laderer v. St. Rita’s Med. Ctr., 702 N.E.2d 476, 483 (Ohio Ct. App. 1997) (finding “expert testimony is needed on complex issues outside the area of common knowledge, such as an injury’s cause and effect.”), and Novak v. United States, 865 F.2d 718, 724 (6th Cir. 1989) (“The burden is upon the plaintiff in this case to establish proximate cause, and because it involves a medical condition or illness, the plaintiff must show by a reasonable degree of medical certainty that the disease was caused by the negligence of the government and/or by its defective product.”).

See also Kerpelis v. Pfizer, Inc., 2004 WL 1326771, at *4 (Ohio Ct. App. June 7, 2004) (holding that in a pharmaceutical drug case questions of defect and “proximate cause of an injury are questions which lie outside the knowledge of lay witnesses [and therefore plaintiffs] would have to introduce expert testimony to establish these elements….”).


See Carver v. Kia Motors Corp., 2012 WL 119587, at *6 (N.D. Okla. Jan. 12, 2012) (holding that when the issue of a product defect involves “complex mechanical, medical, and biomechanical questions that are beyond a jury’s ordinary knowledge and common experience, expert testimony is the best evidence of general causation”); Williams v. Safeway Stores, Inc., 515 P.2d 223, 227 (Okla. 1973) (holding that “where injuries are of a character that medical experts are required to determine the cause and extent of those injuries, the question is one of science to be established by the testimony of skilled professionals”); Delano v. Smith & Nephew, Inc., 2000 WL 689692, at *1 (Okla. Dist. May 12, 2000) (granting summary judgment for defendant-manufacturers in spinal fixation device case where plaintiff failed to present expert testimony as to causation of injuries alleged).


“The requirement of [expert] testimony, we explained in Baughman, is designed to prevent ‘jurors from speculating about causation in cases where that determination requires expertise beyond the knowledge and experience of an ordinary lay person.”’ Hudjohn v. S&G Mach. Co., 114 P.3d 1141, 1148 (Or. Ct. App. 2005) (quoting Baughman v. Pina, 113 P.3d 459, 460 (Or. Ct. App. 2005)); see also Uris v. State Compensation Dep’t, 427 P.2d 753 (Or. 1967) (“[W]here injuries complained of are of such character as to require skilled and professional persons to determine the cause and extent thereof, the question is one of science and must necessarily be determined by testimony of skilled professional persons.”).


Penn. Dep’t of Gen. Servs. v. U.S. Mineral Prod. Co., 898 A.2d 590, 606 (Pa. 2006) (expert testimony required in circumstances in which the subject matter involves special skill and training beyond that possessed by lay persons); Toogood v. Owen J. Rogal, D.D.S., P.C., 824 A.2d 1140, 1149 (Pa. 2003) (“The cause and effect of a physical condition lies in a field of knowledge in which only a medical expert can give a competent opinion…[without experts] we feel that the jury could have no basis other than conjecture, surmise or speculation upon which to consider causation.”); Tennis v. Fedorwicz, 592 A.2d 116 (Pa. Cmwlth. 1991) (requiring expert testimony to prove negligent design); Brandon v. Ryder Truck Rental, Inc., 34 A.3d 104, 110 (Pa. Super. Ct. 2011) (requiring expert testimony to prove injury is proximately caused by a specific defect in the manufacture or design of a product); Burton v. Danek Med., Inc., 1999 WL 118020, at *2 (E.D. Pa. Mar. 1, 1999) (“Absent admissible expert testimony that the Danek device caused [plaintiff husband’s] injuries, Plaintiffs are unable to prevail on any of their claims.”).

Puerto Rico

“The necessity of expert opinion evidence, however, is whether the question is one of common knowledge such that lay people could ‘reach the conclusion as intelligently as the witness.’ If the question cannot be answered by common experience, then expert testimony is required.” Velazquez v. Abbott Labs.,901 F. Supp. 2d 279, 293 (D.P.R. 2012) (quoting Collazo-Santiago v. Toyota Motor Corp., 937 F. Supp. 134, 140 (D.P.R. 1996), aff’d, 149 F.3d 23 (1st Cir. 1998) (expert testimony required to establish defect in an airbag)); see also In re Bausch & Lomb Inc. Contacts Lens Solution Prods. Liab. Litig., 693 F. Supp. 2d. 515, 520 (D.S.C. 2010) (applying Puerto Rico law) (same).

Rhode Island

Under Rhode Island law, “expert testimony is required to establish any matter that is not obvious to a lay person and thus lies beyond common knowledge.” Mills v. State Sales, Inc., 824 A.2d 461, 468 (R.I. 2003) (holding that the court does “not hesitate to conclude that the existence of a causal relationship between a particular toxin and its effect on the human body would have to be established through expert testimony”) (citing Boccasile v. Cajun Music Ltd., 694 A.2d 686, 690 (R.I. 1997)).

South Carolina

“To establish defect and unreasonable danger in a medically complex case, plaintiff must come forward with relevant and reliable expert testimony on these issues.” Disher v. Synthes (U.S.A.), 371 F. Supp. 2d 764, 769 (D.S.C. 2005); see also In re Lipitor (Atorvastatin Calcium) Mktg., Sales Practices and Prods. Liab. Litig., 227 F. Supp. 3d 452, 478–79, 486 (D.S.C. 2017) (South Carolina-based MDL court holding that state law generally requires expert testimony to prove general and specific causation in consolidated litigation where plaintiffs argued pharmaceutical drug was causing diabetes), aff’d, 892 F.3d 624 (4th Cir. 2018); In re Bausch & Lomb Inc. Contacts Lens Solution Prods. Liab. Litig., 693 F. Supp. 2d 515, 518 (D.S.C. 2010) (quoting Goewey v. United States, 886 F. Supp. 1268, 1279 (D.S.C. 1995) (“Where a medical causal relation issue is not one within the common knowledge of the layman, proximate cause cannot be determined without expert medical testimony.”).

South Dakota

“Indeed, expert testimony is ordinarily required to establish a claim of negligence in a product liability action.” Burley v. Kytec Innovative Sports Equip., Inc., 737 N.W.3d 397, 408 (S.D. 2007) (holding that plaintiff needed expert testimony to prove defect and causation because “expert testimony [was] required to identify for the jury how the purportedly defective hook was the proximate or legal cause of [plaintiff’s] injuries”) (citing Caldwell v. John Morrell & Co., 489 N.W.2d 353, 362 (S.D. 1992) (holding that expert testimony is required when the issue falls outside the common experience of a jury)).


“Where ‘neither lay people nor courts possess reliable common knowledge’ plaintiff must proffer expert testimony to prove defectiveness. ‘[C]omplex medical device[s]’ are one product category where Tennessee courts require expert testimony.” Taylor v. Merck & Co., 2009 WL 3429685, at *3 (W.D. Tenn. Oct. 16, 2009) (quoting Fulton v. Pfizer Hosp. Prod. Grp., Inc., 872 S.W.2d 908, 912 (Tenn. Ct. App. 1993); see also Thomas v. Aetna Life & Cas. Co., 812 S.W.2d 278, 283 (Tenn. 1991) (“Medical causation and permanency of an injury must be established in most cases by expert medical testimony”); Miller v. Choo Choo Partners, L.P., 73 S.W.3d 897, 901 (Tenn. Ct. App. 2001) (“As a general rule, the causation of a medical condition must be established by testimony from a medical expert.”).


Taylor v. TMJ Implants, Inc., 1999 WL 351673, at *5 (Tex. Ct. App. 1999) (in lawsuit against manufacturer of jaw implant, “expert testimony was necessary to establish a causal nexus between the alleged defective design and marketing of [the device] and Plaintiffs’ injuries, if any.”); Kimble v. Danek Med., Inc., 2000 WL 1468675, at *3 (S.D. Tex. Sept. 7, 2000) (expert testimony necessary “because the effect of the implantation of a TSRH device during spinal fusion surgery is not ‘a matter of common knowledge [or]…within the experience of a layperson….’”) (citation omitted); Wells v. SmithKline Beecham Corp., 2009 WL 564303, at *5 (W.D. Tex. Feb 18, 2009), aff’d, 601 F.3d 375 (5th Cir. 2010) (“Evidence of general causation in a drug case must be established through expert testimony.”);

A number of cases have discussed the need for expert testimony in the context of highly technical matters of design and engineering, and where such a situation presents itself, uniformly and properly require expert testimony. The reasoning behind those reside principally on the idea that a lay person’s general experience and common sense will not enable that person to determine causation.

Seital Data, Ltd. v. Simmons, 362 S.W.3d 782, 789 (Tex. Ct. App. 2012) (collecting Texas appellate cases);

Mack Trucks, Inc. v. Tamez, 206 S.W.3d 572, 582 (Tex. 2006) (“Expert testimony is required when an issue involves matters beyond jurors’ common understanding”).


Niemela v. Imperial Mfg., Inc., 263 P.3d 1191, 1199 (Utah Ct. App. 2011) (“Depending on the nature of the injury, establishing the causal link between negligence and injury often requires expert testimony. It is only in the most obvious cases that a plaintiff may be excepted from the requirement of using expert testimony to prove causation.”) (internal quotations and citations omitted); Christison v. Biogen Idec, Inc., 199 F. Supp. 1315, 1342 (D. Utah 2016) (dismissing failure to warn claim in drug case for lack of expert testimony because “an expert is required to determine the adequacy of the warning. Specifically, it requires an expert who is familiar with drug labeling and the process by which a drug is prescribed to a patient.”); Hoopiiaina v. Intermountain Health Care, 740 P.2d 270, 271 (Utah Ct. App. 1987) (holding in a pharmaceutical drug case that “[b]ecause these matters are outside the knowledge and experience of laypeople, expert medical testimony was required to establish causation, the standard of care, and its breach.”).


When the facts to be proved are such that any layman of average intelligence would know from his own knowledge and experience that the accident was the cause of the injury, no expert testimony is needed to establish the causal connection; however, where the causal connection is obscure, expert testimony is required.

Egbert v. Book Press, 477 A.2d 968, 969 (Vt. 1984) (quoting Houghton v. Leinwohl, 376 A.2d 733, 737 (Vt. 1977)).

Thus, the District of Vermont granted summary judgment in a pharmaceutical drug case because the proffered expert opinion was not reliable: “Without expert testimony that [the drug] caused the death, it is not possible to show that any inadequacy in warning [about the drug] was a substantial factor in bringing about the deaths.” Blanchard v. Eli Lilly & Co., 207 F. Supp. 2d 308, 322 (D. Vt. 2002). Relatedly, Vermont law requires expert testimony in medical malpractice cases. See e.g., Noyes v. Gaugnon, 2008 WL 2811231, at *1 (Vt. 2008) (“Except where the alleged violation of the standard of care is so apparent that it can be understood by a layperson without the aid of medical experts, the burden of proof imposed by [the statute] requires expert testimony”) (internal citations omitted).


“Proof of legal causation in a medical device case must be by expert testimony and the expert’s opinion must be stated in terms of reasonable probability.” Hartwell v. Danek Med., Inc., 47 F. Supp. 2d 703, 707 (W.D. Va. 1999); Smith v. Gen. Motors Corp., 376 F. Supp. 2d 664, 667 (W.D. Va. 2005) (“Modern case law requires expert medical testimony to establish causation in cases where the plaintiff has suffered a complex injury.”); McCauley v. Purdue Pharma L.P., 331 F. Supp. 2d 449, 464 (W.D. Va. 2004) (“[I]n a products liability action, proof of causation must ordinarily be supported by expert testimony because of the complexity of the causation facts.”).


Expert testimony is required to establish causation when an injury involves obscure medical factors that would require an ordinary lay person to speculate or conjecture in making a finding…This required expert testimony [regarding medical causation] must provide proof that the defect “more probably than not” caused [plaintiffs’] injuries. Less certain evidence, such as may, might, could or possibly, does not provide enough guidance to the jury to remove the decision-making process from speculation and conjecture.

Bruns v. PACCAR, Inc., 890 P.2d 469, 477 (Wash. Ct. App. 1995) (quoting O’Donoghue v. Riggs, 440 P.2d 823, 840 (Wash. 1968) and citing Riggins v. Bechtel Power Corp., 722 P.2d 819 (Wash. Ct. App. 1986)).

See also Luttrell v. Novartis Pharms. Corp., 894 F. Supp. 2d 1324, 1340 (E.D. Wash. 2012) (requiring expert testimony on causation in pharmaceutical drug case).

West Virginia

Rohrbough v. Wyeth Labs., Inc., 916 F.2d 970, 972 (4th Cir. 1990) (West Virginia case) (“An essential element of plaintiffs’ cause of action is proof that defendant’s vaccine caused plaintiff’s injuries, and proof of causation must be by expert testimony.”) (citing Hicks v. Chevy, 358 S.E.2d 202, 205 (W. Va. 1987)); Watson v. Inco Alloys Int’l, Inc.,545 S.E.2d 294, 297 (W. Va. 2001) (holding in a design defect forklift case that “medical causation and injury enhancement testimony requires testimony of a medical expert”); Jenkins v. CSX Transp., Inc., 649 S.E.2d 294, 297 (W. Va. 2007) (holding in a Federal Employers Liability Act action where plaintiff alleged exposure to toxins that expert testimony was required to establish medical causation “upon a reasonable certainty that the injury resulted from the negligence of the defendant.”); Farley v. Shook, 629 S.E.2d 739, 745 (W. Va. 2006) (noting in a complex medical malpractice case, that it was “clear that the nature of the case required expert testimony.”).


In cases involving “technical, scientific, or medical matters which are beyond the common knowledge or experience of jurors,” Wisconsin law requires expert testimony to establish causation. Smith v. Sofamor, S.N.C., 21 F. Supp. 2d 918, 921 (W.D. Wis. 1998) (quoting Ollman v. Wis. Health Care Liab. Ins. Plan, 505 N.W.2d 399, 405 (Wis. Ct. App. 1993)); see also Iverson v. Smith & Nephew, Inc., 2016 WL 4083523, at *1 (W.D. Wis. Aug. 1, 2016) (holding that plaintiffs needed expert testimony because the cases involved “complex issues about a medical device that are well outside the knowledge and experience of a lay person”); Johnson v. Mylan Inc., 107 F. Supp. 3d 967, 974 (E.D. Wis. 2015) (holding that in a lawsuit against the manufacturer of a prescription transdermal fentanyl patch “the plaintiffs needed to support their claims with expert testimony in order to proceed to trial”); Valente v. Sofamor, S.N.C., 48 F. Supp. 2d 862, 867 (W.D. Wis. 1999) (holding “plaintiffs must present expert testimony establishing causation between their injuries and defects”).


In Rohde v. Smiths Med, the Wyoming Supreme Court affirmed summary judgment granted in a medical device case because plaintiff had failed to present expert testimony on specific defect or to rule out other potential causes with expert testimony to obtain an inference of defect. See Rohde v. Smiths Med., 165 P.3d 433, 440 (Wyo. 2007). Specifically, the court explained “if the [catheter] was defectively designed making it prone to fracture then, presumably, [the plaintiff] could have located an expert to analyze the design and provide his opinion on such a specific defect” or plaintiff “could have qualified for an inference of defect by presenting expert evidence to discount the other causes of the fracture identified by [the defendant].” Id.; see also Ronwin v. Bayer Corp., 332 F. App’x 508, 514 (10th Cir. 2009) (applying Wyoming law) (excluding plaintiff’s expert and affirming summary judgment in pharmaceutical drug case). The plaintiff in Ronwin was not able to “identify any error in the district court’s conclusion that absent expert testimony on causation, summary judgment was appropriate.” Id. The trial court determined that expert testimony would be required under Wyoming law by reviewing medical malpractice case law. See id. (citing Sayer v. Williams, 962 P.2d 165, 167 (Wyo. 1998) (holding in medical malpractice case that, “[s]ince [plaintiff’s] high blood pressure and Hepatitis C could very well have caused the symptoms of which she complained, expert testimony remained essential to the establishment of proximate cause.”); see also, e.g., Hayes v. State ex rel. Wyo. Workers’ Safety & Comp. Div., 307 P.3d 843, 850 (Wyo. 2013) (“The present case involves complex issues related to cystic fibrosis, infection and the physical effects of tasing, making medical evidence necessary to establish causation.”).


Peter A. Meyer is a partner and Eldin Hasic is an associate at Faegre Baker Daniels Fort Wayne, Indiana.

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