Practice Tip: Admissibility of Expert Opinions

An examination of recent federal and state court decisions on the admissibility of expert witness opinions can help lawyers properly develop their own experts and successfully exclude an adversary's experts before trial. The purpose of this article is to provide an update of the themes and factors that were important to courts in 2009 in reaching their decisions on the admissibility of expert witness opinions. (It is assumed that the reader of this article has a basic understanding of the legal standards regarding admissibility of expert witness opinions.)

Is the Expert Qualified?

Under any admissibility standard, the court must first decide whether or not the expert is qualified to give the opinion. Recent decisions highlight areas for consideration when assessing this threshold question.

Does the Expert Have Specialized Training in the Relevant Field in Which He/She Is Giving an Opinion?

Several courts found that an expert's lack of specialized training rendered him or her unqualified to give an opinion. See, e.g., Ronwin v. Bayer Corp., 332 Fed. Appx. 508 (10th Cir. 2009) (pharmaceutical product liability case where expert surgeon with no experience with Baycol or statins was not qualified to render an opinion about the effects of those drugs); Lewis v. Citgo Petroleum Corp., 561 F.3d 698 (7th Cir. 2009) (chemical exposure case where an expert allergist with no training or experience in toxicology or epidemiology was not qualified to render causation opinion); Haller v. AstraZeneca Pharms., LP, 598 F. Supp. 2d 1271 (M.D. Fla. 2009) (pharmaceutical product liability case where psychiatrist expert with no specialized training in how to diagnose the cause of a patient's diabetes was not qualified to give causation opinion regarding plaintiff diabetes); but see In re Fosamax Prods. Liab. Litig., 645 F. Supp. 164 (S.D.N.Y. 2009) (pharmaceutical product liability case where expert was deemed qualified to opine on drug's clinical trial data as it related, generally, to bone fracture reduction efficacy, despite the fact that the expert did not treat patients for osteoporosis or bone density issues).

Is the Expert's Experience in the Field Outdated?

In Ronwin, the court found that an expert was not qualified to give a causation opinion because the expert had not been in active private practice for over 30 years. 332 Fed. Appx. 508.

Mistakes, Sloppy Preparation Can Sink the Ship

An expert's isolated and minor mistake usually will not lead to the exclusion of the expert's opinion. But as several 2009 cases demonstrate, the cumulative effect of multiple mistakes, compounded by sloppiness in preparation, can prove fatal. Examples of mistakes and poor preparation that factored into the courts' ultimate decisions to exclude the experts opinions include: 1) the expert did not examine or speak with the plaintiff, Haller, 598 F. Supp. 2d 1271; 2) the expert failed to review all of the plaintiff's medical records, Id.; Lewis, 561 F.3d 698; 3) the expert failed to review all of the depositions of plaintiff treating physicians, Haller, 598 F. Supp. 2d 1271; 4) the expert failed to review the medical literature on the product in question comprehensively (review of only a small portion was deemed insufficient), Id.; 5) the expert's report contained factual errors regarding key facts in the plaintiff's case, Id.; Legget v. Eli Lilly & Co., 2009 U.S. Dist. LEXIS 40125 (E.D.N.Y. May 12, 2009); 6) the expert failed to conduct appropriate data analysis and/or testing of the product, Presley v. Lakewood Eng & Mfg. Co., 553 F.3d 638 (8th Cir. 2009); In re Bausch & Lomb Contact Lens Solution Prod. Liab. Litig., 2009 U.S. Dist. LEXIS 83849 (D.S.C. Aug. 26, 2009); In re Bausch & Lomb Contact Lens Solution Prod. Liab. Litig., 2009 N.Y. Misc. LEXIS 3407 (N.Y. Sup. Ct. July 15, 2009); and 7) the expert did not conduct any independent research, but instead relied upon articles provided by others, Kilpatrick v. Breg, Inc., 2009 U.S. Dist. LEXIS 76128 (S.D. Fla. June 25, 2009).

These cases highlight the importance of digging into an expert's report, determining what the expert actually reviewed and did not review and checking the accuracy of all of the facts cited by the expert in support of his or her opinion.

Have You Covered All the Bases for That Opinion?

An expert's opinion that is based on incomplete and unreliable information is subject to exclusion. In addition to a close look at the accuracy and reliability of all of the materials upon which an expert has based his or her opinion, it also is critical to conduct a thorough search to see if the expert failed to account for any information that undercuts and contradicts the opinion.

In 2009 product liability cases, experts' causation opinions were excluded both because of what they were and were not based on. For example, some courts excluded opinions based on the expert's improper extrapolation from epidemiological studies that did not have a control group, e.g., in vitro and animal studies. In re Bausch & Lomb, 2009 N.Y. Misc. LEXIS 3407; Kilpatrick, 2009 U.S. Dist. LEXIS 76128; Rimbert, 2009 U.S. Dist. LEXIS 68851 (also holding that a study finding only an association was an insufficient basis for expert's causation opinion). But several courts held differently, and found that experts' opinions had adequate bases where, in the absence of epidemiological studies with control groups, the experts based their opinions on the best available scientific evidence, including animal studies and case reports. In re Fosamax, 645 F. Supp. 164; General Motors Corp. v. Greiner, 981 A.2d 531 (Del. 2009); McCarrell v. Hoffman-La Roche, Inc., 2009 N.J. Super. Unpub. LEXIS 558 (N.J. App. Div. March 12, 2009). One court criticized an expert for not reviewing comprehensively and addressing all of the available medical and scientific literature on the product and the alleged injury, including studies that undercut and contradicted the expert's opinion. Haller, 598 F. Supp. 2d 1271.

What's Your Methodology?

Whether an expert opinion is subject to Daubert, Frye, or some other standard, the adequacy of the expert's overall methodology in reaching an opinion is a key question for determining admissibility. Decisions in 2009 highlighted several important methodological flaws and shortcomings, all of which should be considered when you are engaged in expert discovery.

An expert's failure to rule out the possibility that a plaintiff's independent risk factors were the sole cause of the injury was found to be a flawed methodology. Ronwin, 332 Fed. Appx. 508; Haller, 598 F. Supp. 2d 1271; Guinn v. AstraZeneca Pharms., LP, 598 F. Supp. 2d 1239 (M.D. Fla. 2009); Fuesting, 594 F. Supp. 2d 1043; Rimbert, 2009 U.S. Dist. LEXIS 68851. In these same cases, admissions by experts that it was more likely than not that a plaintiff would have someday developed the same injury in the absence of using the defendant's product also contributed to the finding of an overall flawed methodology. See also, Kilpatrick, 2009 U.S. Dist. LEXIS 76128 (court found methodology was flawed where the expert could not account for the background risk of the injury in reaching a general causation opinion); and see Lewis, 561 F.3d 698 and Guinn, 598 F. Supp. 2d 1239 (expert's failure to quantify the contributions of a plaintiff independent risk factors contributed to court's finding that the methodology was flawed).

Two courts also found flawed methodologies when experts' specific causation opinions were based solely on the mere temporal association between plaintiffs' use of defendants' products and the development of the alleged injuries. Haller, 598 F. Supp. 2d 1271; Kilpatrick, 2009 U.S. Dist. LEXIS 76128. One court found that an expert's failure to identify a mechanism of causation for a specific plaintiff was a factor that weighed against the adequacy of the expert's methodology. Guinn, 598 F. Supp. 2d 1239.

While a differential diagnosis methodology is deemed generally accepted in most jurisdictions, it still must be performed properly. Two courts found that a differential diagnosis methodology was not properly performed when an expert did not first rule in all substantial and legitimate causes of the injury and then rule out causes other than the product at issue. Ronwin, 332 Fed. Appx. 508; Rimbert, 2009 U.S. Dist. LEXIS 68851. Another court found that a differential diagnosis methodology was properly performed where the expert: 1) objectively ascertained the nature of the plaintiff's injury; 2) ruled in the potential causes of the injury; and 3) engaged in standard and accepted diagnostic techniques which doctors normally use to rule out alternative causes in order to reach an opinion as to which cause was most likely. Best v. Lowe Home Ctrs., Inc., 563 F.3d 171 (6th Cir. 2009).

Several courts criticized the methodologies of experts who, for the purposes of litigation, departed from the methods they routinely used in their private practices to reach opinions on causation. In re Fosamax Prods. Liab. Litig., 645 F. Supp. 164; Haller, 598 F. Supp. 2d 1271; Rimbert, 2009 U.S. Dist. LEXIS 68851.

In another case, a court disapproved of an expert's methodology when the expert's opinion evolved and changed over time in response to the adverse party's motion practice to exclude the opinion. Haller, 598 F. Supp. 2d 1271. Similarly, another court found that reaching an opinion solely for litigation purposes was a factor that weighed against the adequacy of the expert's methodology. Rimbert, 2009 U.S. Dist. LEXIS 68851. Failure by an expert to publish his opinions and subject them to peer-review was another factor that two courts weighed against the adequacy of experts' methodologies. In re Bausch & Lomb, 2009 N.Y. Misc. LEXIS 3407; Rimbert, 2009 U.S. Dist. LEXIS 68851.

The Takeaway

These 2009 product liability cases tell us that courts will take the time to digest the details that lawyers develop during expert discovery. Lawyers should dig into an expert's background and qualifications. For some courts, an expert's factual errors and failure to review relevant information will at some point reach a level that triggers the exclusion of the expert's opinion. Lawyers should, therefore, thoroughly fact-check an expert's report, conduct independent research for important information that an expert may have failed to consider, and pin the expert down on what he or she did and did not review before reaching an opinion.

The adequacy of the expert's methodology continues to be a central inquiry, particularly for expert causation opinions in product liability cases. Lawyers should test and challenge the expert's methodology, e.g., by having the expert specifically articulate how he or she was able to rule out plaintiff's independent risk factors as the sole cause of the injury. Lawyers who are deposing experts should focus more on the expert's methodology than on the expert's ultimate conclusions. Lawyers should pin the expert down and make the expert restate his or her methodology when the expert's answers are vague and elusive. And when faced with an expert who employs a generally accepted methodology, lawyers should determine whether the expert properly followed the methodology in reaching his or her opinion.

These 2009 cases also highlight lawyers' successes with specific causation challenges. While this does not mean one should concede general causation, these cases nevertheless show that a lawyer can likely be more successful in excluding expert witnesses on the basis of specific causation.

David Uitti is an associate in the Mass Tort and Product Liability group of Dechert LLP, resident in the Princeton, NJ, office. He can be reached at [email protected].

An examination of recent federal and state court decisions on the admissibility of expert witness opinions can help lawyers properly develop their own experts and successfully exclude an adversary's experts before trial. The purpose of this article is to provide an update of the themes and factors that were important to courts in 2009 in reaching their decisions on the admissibility of expert witness opinions. (It is assumed that the reader of this article has a basic understanding of the legal standards regarding admissibility of expert witness opinions.)

Is the Expert Qualified?

Under any admissibility standard, the court must first decide whether or not the expert is qualified to give the opinion. Recent decisions highlight areas for consideration when assessing this threshold question.

Does the Expert Have Specialized Training in the Relevant Field in Which He/She Is Giving an Opinion?

Several courts found that an expert's lack of specialized training rendered him or her unqualified to give an opinion. See, e.g., Ronwin v. Bayer Corp. , 332 Fed. Appx. 508 (10th Cir. 2009) (pharmaceutical product liability case where expert surgeon with no experience with Baycol or statins was not qualified to render an opinion about the effects of those drugs); Lewis v. Citgo Petroleum Corp. , 561 F.3d 698 (7th Cir. 2009) (chemical exposure case where an expert allergist with no training or experience in toxicology or epidemiology was not qualified to render causation opinion); Haller v. AstraZeneca Pharms., LP , 598 F. Supp. 2d 1271 (M.D. Fla. 2009) (pharmaceutical product liability case where psychiatrist expert with no specialized training in how to diagnose the cause of a patient's diabetes was not qualified to give causation opinion regarding plaintiff diabetes); but see In re Fosamax Prods. Liab. Litig., 645 F. Supp. 164 (S.D.N.Y. 2009) (pharmaceutical product liability case where expert was deemed qualified to opine on drug's clinical trial data as it related, generally, to bone fracture reduction efficacy, despite the fact that the expert did not treat patients for osteoporosis or bone density issues).

Is the Expert's Experience in the Field Outdated?

In Ronwin, the court found that an expert was not qualified to give a causation opinion because the expert had not been in active private practice for over 30 years. 332 Fed. Appx. 508.

Mistakes, Sloppy Preparation Can Sink the Ship

An expert's isolated and minor mistake usually will not lead to the exclusion of the expert's opinion. But as several 2009 cases demonstrate, the cumulative effect of multiple mistakes, compounded by sloppiness in preparation, can prove fatal. Examples of mistakes and poor preparation that factored into the courts' ultimate decisions to exclude the experts opinions include: 1) the expert did not examine or speak with the plaintiff, Haller, 598 F. Supp. 2d 1271; 2) the expert failed to review all of the plaintiff's medical records, Id.; Lewis, 561 F.3d 698; 3) the expert failed to review all of the depositions of plaintiff treating physicians, Haller, 598 F. Supp. 2d 1271; 4) the expert failed to review the medical literature on the product in question comprehensively (review of only a small portion was deemed insufficient), Id.; 5) the expert's report contained factual errors regarding key facts in the plaintiff's case, Id.; Legget v. Eli Lilly & Co., 2009 U.S. Dist. LEXIS 40125 (E.D.N.Y. May 12, 2009); 6) the expert failed to conduct appropriate data analysis and/or testing of the product, Presley v. Lakewood Eng & Mfg. Co. , 553 F.3d 638 (8th Cir. 2009); In re Bausch & Lomb Contact Lens Solution Prod. Liab. Litig., 2009 U.S. Dist. LEXIS 83849 (D.S.C. Aug. 26, 2009); In re Bausch & Lomb Contact Lens Solution Prod. Liab. Litig., 2009 N.Y. Misc. LEXIS 3407 (N.Y. Sup. Ct. July 15, 2009); and 7) the expert did not conduct any independent research, but instead relied upon articles provided by others, Kilpatrick v. Breg, Inc., 2009 U.S. Dist. LEXIS 76128 (S.D. Fla. June 25, 2009).

These cases highlight the importance of digging into an expert's report, determining what the expert actually reviewed and did not review and checking the accuracy of all of the facts cited by the expert in support of his or her opinion.

Have You Covered All the Bases for That Opinion?

An expert's opinion that is based on incomplete and unreliable information is subject to exclusion. In addition to a close look at the accuracy and reliability of all of the materials upon which an expert has based his or her opinion, it also is critical to conduct a thorough search to see if the expert failed to account for any information that undercuts and contradicts the opinion.

In 2009 product liability cases, experts' causation opinions were excluded both because of what they were and were not based on. For example, some courts excluded opinions based on the expert's improper extrapolation from epidemiological studies that did not have a control group, e.g., in vitro and animal studies. In re Bausch & Lomb, 2009 N.Y. Misc. LEXIS 3407; Kilpatrick, 2009 U.S. Dist. LEXIS 76128; Rimbert, 2009 U.S. Dist. LEXIS 68851 (also holding that a study finding only an association was an insufficient basis for expert's causation opinion). But several courts held differently, and found that experts' opinions had adequate bases where, in the absence of epidemiological studies with control groups, the experts based their opinions on the best available scientific evidence, including animal studies and case reports. In re Fosamax , 645 F. Supp. 164; General Motors Corp. v. Greiner , 981 A.2d 531 (Del. 2009); McCarrell v. Hoffman-La Roche, Inc., 2009 N.J. Super. Unpub. LEXIS 558 (N.J. App. Div. March 12, 2009). One court criticized an expert for not reviewing comprehensively and addressing all of the available medical and scientific literature on the product and the alleged injury, including studies that undercut and contradicted the expert's opinion. Haller, 598 F. Supp. 2d 1271.

What's Your Methodology?

Whether an expert opinion is subject to Daubert, Frye, or some other standard, the adequacy of the expert's overall methodology in reaching an opinion is a key question for determining admissibility. Decisions in 2009 highlighted several important methodological flaws and shortcomings, all of which should be considered when you are engaged in expert discovery.

An expert's failure to rule out the possibility that a plaintiff's independent risk factors were the sole cause of the injury was found to be a flawed methodology. Ronwin, 332 Fed. Appx. 508; Haller , 598 F. Supp. 2d 1271; Guinn v. AstraZeneca Pharms., LP , 598 F. Supp. 2d 1239 (M.D. Fla. 2009); Fuesting, 594 F. Supp. 2d 1043; Rimbert, 2009 U.S. Dist. LEXIS 68851. In these same cases, admissions by experts that it was more likely than not that a plaintiff would have someday developed the same injury in the absence of using the defendant's product also contributed to the finding of an overall flawed methodology. See also, Kilpatrick, 2009 U.S. Dist. LEXIS 76128 (court found methodology was flawed where the expert could not account for the background risk of the injury in reaching a general causation opinion); and see Lewis, 561 F.3d 698 and Guinn, 598 F. Supp. 2d 1239 (expert's failure to quantify the contributions of a plaintiff independent risk factors contributed to court's finding that the methodology was flawed).

Two courts also found flawed methodologies when experts' specific causation opinions were based solely on the mere temporal association between plaintiffs' use of defendants' products and the development of the alleged injuries. Haller, 598 F. Supp. 2d 1271; Kilpatrick, 2009 U.S. Dist. LEXIS 76128. One court found that an expert's failure to identify a mechanism of causation for a specific plaintiff was a factor that weighed against the adequacy of the expert's methodology. Guinn, 598 F. Supp. 2d 1239.

While a differential diagnosis methodology is deemed generally accepted in most jurisdictions, it still must be performed properly. Two courts found that a differential diagnosis methodology was not properly performed when an expert did not first rule in all substantial and legitimate causes of the injury and then rule out causes other than the product at issue. Ronwin, 332 Fed. Appx. 508; Rimbert, 2009 U.S. Dist. LEXIS 68851. Another court found that a differential diagnosis methodology was properly performed where the expert: 1) objectively ascertained the nature of the plaintiff's injury; 2) ruled in the potential causes of the injury; and 3) engaged in standard and accepted diagnostic techniques which doctors normally use to rule out alternative causes in order to reach an opinion as to which cause was most likely. Best v. Lowe Home Ctrs., Inc. , 563 F.3d 171 (6th Cir. 2009).

Several courts criticized the methodologies of experts who, for the purposes of litigation, departed from the methods they routinely used in their private practices to reach opinions on causation. In re Fosamax Prods. Liab. Litig., 645 F. Supp. 164; Haller , 598 F. Supp. 2d 1271; Rimbert, 2009 U.S. Dist. LEXIS 68851.

In another case, a court disapproved of an expert's methodology when the expert's opinion evolved and changed over time in response to the adverse party's motion practice to exclude the opinion. Haller, 598 F. Supp. 2d 1271. Similarly, another court found that reaching an opinion solely for litigation purposes was a factor that weighed against the adequacy of the expert's methodology. Rimbert, 2009 U.S. Dist. LEXIS 68851. Failure by an expert to publish his opinions and subject them to peer-review was another factor that two courts weighed against the adequacy of experts' methodologies. In re Bausch & Lomb, 2009 N.Y. Misc. LEXIS 3407; Rimbert, 2009 U.S. Dist. LEXIS 68851.

The Takeaway

These 2009 product liability cases tell us that courts will take the time to digest the details that lawyers develop during expert discovery. Lawyers should dig into an expert's background and qualifications. For some courts, an expert's factual errors and failure to review relevant information will at some point reach a level that triggers the exclusion of the expert's opinion. Lawyers should, therefore, thoroughly fact-check an expert's report, conduct independent research for important information that an expert may have failed to consider, and pin the expert down on what he or she did and did not review before reaching an opinion.

The adequacy of the expert's methodology continues to be a central inquiry, particularly for expert causation opinions in product liability cases. Lawyers should test and challenge the expert's methodology, e.g., by having the expert specifically articulate how he or she was able to rule out plaintiff's independent risk factors as the sole cause of the injury. Lawyers who are deposing experts should focus more on the expert's methodology than on the expert's ultimate conclusions. Lawyers should pin the expert down and make the expert restate his or her methodology when the expert's answers are vague and elusive. And when faced with an expert who employs a generally accepted methodology, lawyers should determine whether the expert properly followed the methodology in reaching his or her opinion.

These 2009 cases also highlight lawyers' successes with specific causation challenges. While this does not mean one should concede general causation, these cases nevertheless show that a lawyer can likely be more successful in excluding expert witnesses on the basis of specific causation.

David Uitti is an associate in the Mass Tort and Product Liability group of Dechert LLP, resident in the Princeton, NJ, office. He can be reached at [email protected].