Effective strategies for closing the door on junk science experts.

• Author: Parker, Bruce R.

The Daubert decision offers defense counsel an excellent vehicle for excluding junk science, but there are many alternatives to consider

MUCH has been written about the legal standards announced by the U.S. Supreme Court in Daubert v. Merrill Dow Pharmaceuticals(1) and Joiner v. General Electric Co.,(2) but relatively little attention has been afforded to the practical implications of both decisions with respect to deposing and cross-examining at trial an expert whose testimony is subject to a Daubert challenge. This article examines what approaches should be used when deposing or cross-examining at trial experts who have survived a Daubert challenge. For simplicity, let's call such a person a "Daubert expert" and the cross-examination a "Daubert cross."

PRACTICAL ASPECTS

1. Deposing a Daubert Expert

   The Supreme Court's invitation to challenge the admissibility of expert testimony by demonstrating the unreliability of the expert's methodology has made it even more imperative that trial counsel develop expertise on the scientific principles relevant to the expert's testimony. The expertise must be developed--at least substantially so--before the expert is deposed in order to maximize the opportunity to elicit testimony that will support a Daubert challenge.

   Counsel knowledgeable on the relevant scientific principles often will have an advantage at an expert's deposition, particularly when the expert is deposed early in the case. Plaintiffs' attorneys often will not have spent the time to learn the science before their experts are deposed, also particularly when the deposition occurs early in the case. They will not be in a position to have prepared their experts for depositions. In addition, because experts know that most cases settle, many will not prepare for a deposition as thoroughly as they will for trial testimony. These factors create a unique opportunity for deposing defense counsel to extract concessions from the expert that will be critical in having the testimony stricken under Daubert.

   The following discussion is not intended to be an all encompassing outline for deposing Daubert experts. Rather, it's intended to highlight several issues that need to be addressed when deposing Daubert experts.

   1. Have the experts subscribe to the scientific method

      The scientific method is the means by which scientific knowledge is developed. If experts are to survive a Daubert challenge, they must establish that their opinions were formed consistent with the scientific method. The scientific method involves the formation of a hypothesis or theory--referred to as the "null" hypothesis--which is then subject to rigorous controlled testing. Data generated by the testing are statistically analyzed to determine if they are statistically meaningful. If data are statistically meaningful, additional factors must be evaluated to determine their biological importance.

      Experts who subscribe to the scientific method will be hard pressed to argue credibly that data not statistically significant or generated by uncontrolled studies provide an adequate basis on which to reach scientific conclusions.

   2. Demonstrate that experts' opinions are unreliable because of their unfamiliarity with the underlying theory

      It often is a judgment call whether to explore certain issues with an expert on deposition or to wait until a Daubert hearing. Many experienced defense trial counsel would prefer to leave to the Daubert hearing and not address in a deposition the degree (or lack thereof) of experts' knowledge in the substantive area relevant to their opinions. These lawyers view the deposition as a means to have experts state all their opinions, leaving for trial a challenge to the validity of the opinions. If, however, counsel can get experts to concede at deposition that they do not understand the scientific theory underlying the test that generated the data on which they rely, then their testimony should not be admissible.(3)

   3. Demonstrate that the theory has not been subject to adequate and/or objective scientific testing

      Experts who subscribe to the scientific method will be forced to concede that an opinion lacking empirical validation is not supported by scientific data. In most cases, however, experts will contend there has been some degree of testing that has generated data to support their theory. In those cases, defense counsel must obtain the raw data on which the opinion is predicated. In matters involving sophisticated and complex testing, defense counsel should get an order requiring the expert to produce the data in advance of the deposition so that it can be reviewed by defense counsel's expert. If the data is not produced before the deposition, defense counsel should consider having their expert attend the deposition. The expert may be able to analyze the data at least preliminarily during the deposition and provide counsel with advice regarding deficiencies in the data.

   4. If the experts' theories have been tested, show that the data have not been validated by others

      A fundamental principle of science is that before data can be considered valid, they must be reproducible. It is important to ascertain if others have attempted to validate the assay or technique and, if so, the results. Experts often evade this inquiry by emphasizing the highly statistical significance of the data. It is not, however, a substitute for reproducibility of data for experts to argue that the data are statistically significant at the 99 percent level. Meaningless data can be "statistically significant."

      In addition, defense counsel should not accept at face value experts' testimony that the data were validated by "independent" laboratories. Deposing the "independent" labs often reveals evidence of bias, poor study design and questionable lab techniques.

   5. Determine whether the data were properly statistically analyzed

      With few, if any, exceptions, scientific data that have not been properly statistically analyzed should not be admissible under Daubert. The scientific method requires that the results produced by an experiment be statistically significant. By convention this is set at a probability (P) level of 5 percent. In other words, the difference between two or more results must be such that the odds of obtaining the results by chance alone are not greater than 1 in 20 (i.e., [is less than or equal to] .05).

      Questioning experts on the statistical significance of data on which they have relied is often a fruitful area of examination. Because of the complexity of statistical testing, most investigators rely on a biostatistician to evaluate their data. When data have not been subjected to peer review and the expert has not performed the statistical analysis, the expert will not be able to lay the proper foundation under Daubert to rely on the data.

      It is beyond the scope of this paper to offer a primer on biostatistics, but statistical evidence is often misused by experts in drug and medical device litigation and is a fertile area for cross-examination. Areas include poor study design, inappropriate statistical analysis of the data and statistical manipulation of data to create statistical significance.(4)

   6. Determine whether the assay or equipment is accepted within the scientific community

      There are several lines of inquiry that can produce testimony that an assay or technique has not achieved general acceptance in the scientific community. The following questions highlight areas that, depending upon the nature of the experiment, instrument or assay, may be helpful in demonstrating that opinions based on the data generated by an instrument, assay or experiment do not constitute "scientific knowledge" under Daubert.

      (a) Has the assay been approved by the appropriate government agency?

      Immunoassay kits that are sold or otherwise used for diagnostic purposes are subject to FDA regulation. Manufacturers of unapproved assays often receive FDA regulatory letters. These letters typically describe the assay as experimental and not suitable for diagnostic purposes. An assessment by the FDA that the assay is experimental should help counsel convince a court of its unreliability under Daubert.

      (b) Has the expert modified a standard assay to develop the data?

      Experts often claim that their testimony is admissible under Daubert because it is predicated on tests that have been accepted for many years. Footnote 11 of Justice Blackmun's opinion in Daubert strongly suggests, however, that, although Frye(5) applied exclusively to novel scientific techniques, Daubert principles apply to all scientific knowledge. As one commentator has noted, "scientific techniques cannot be `grandfathered' in under Daubert."(6) In some cases, experts derive data from conventional assays that have been modified. Modifying an assay to test something for which it was not developed renders the data as unreliable as if the assay had just been developed.

      Explore in the deposition how the assay was modified, the purpose for the modification, whether preliminary experiments to optimize the kinetics of the assay were performed, the results of the preliminary assays and whether internal controls or standards were used when the assay was run.

      (c) Was the experiment properly designed and performed?

      There are many factors that are essential to a well-designed and performed experiment. A critical feature of a well-designed study is the appropriate selection and number of controls. An experiment that is not properly controlled will not produce reliable data. Experts should be able to identify the variables the investigators sought to control and how the controls were selected. The greater the number of uncontrolled variables, the less reliable is the data. Experts should not be permitted to rely on experimental data to express an opinion if they cannot explain how (1) the study was designed, (2) the controls were selected and (3) the experiment was performed.

      An experiment, to the...