Daubert Challenges – A Professional Perspective

Joseph O'Neill

Written by
— Updated on June 22, 2020

Daubert ChallengeSince Daubert v. Merrell Dow Pharmaceuticals in 1993, the Frye “general acceptance” test has been superceded by the newer Daubert standard for the admissibility of expert evidence on the federal level and in more than half of U.S. state courts. The older Frye standard held the measure of reliable expert testimony by the norms of the scientific community. However, Daubert makes the judge a “gatekeeper” of admissible evidence, determining how reliable the expert’s conclusions are based on his or her use of sound “scientific methodology.”. As a result, a proper understanding of Daubert and its standards for expert testimony is a vital part of working with – and serving as – an expert witness.

Below, we’ve compiled some professional insights from both attorneys and experts to help you understand and avoid a Daubert challenge.


Daubert Challenge Laurence DeutschDaubert challenges are disfavored in my own field of practice (medical malpractice). Strictly speaking, New York applies the “Frye” test as opposed to “Daubert”  (expert testimony based on scientific principles or procedures is admissible but only after a principle or procedure has gained general acceptance in its specified field.” Lugo v New York City Health and Hospitals Corporation, 89 AD3d 42 [2nd Dept 2011]). However, there is some convergence in the actual application of the “Frye” and “Daubert” doctrines. More often than not, New York medical malpractice cases involve a “battle of the experts”. Probably because of this, our medical malpractice Judges tend to give the Jury more deference to evaluate the credibility of expert opinion than in some other areas of practice (e.g. Products liability) in which the Judges tend to take a more “activist” stance to evaluate expert testimony.

There are situations in which novel or unsupported theories may be excluded in malpractice cases. And, it is not always Plaintiffs that are on the wrong end of a Daubert challenge. Recently there was an important decision keeping out what I would call a “junk defense” in obstetrical malpractice cases.  Defendants would argue that the “forces of labor” could cause major brachial plexus injury (disabling injury to nerves of the arm) having nothing to do with the manner of delivery (Muhammad v Fitzpatrick, 91 AD3d 1353 [4th Dept 2012]). However, some Courts have still allowed this theory to be presented to a Jury. This is based on the level of proof presented on the issue of “general acceptance”  See, Nobre v. Shanahan, 2013 NY Slip Op  23433).

The New York Federal Courts tend to be much more receptive to Daubert challenges than their State counterparts. They apply the Daubert standards as codified in the Federal Rules (FRCP 702-705). My firm succeeded in excluding both engineering expert opinion and a psychiatrists expert opinion in a Federal medical malpractice case (arising from surgery at a Veterans Administration hospital). In that case, the Court excluded a proposed defense engineer’s opinions to the effect that our client “could not fit” in a CT scan (that we say should have been ordered) based on measurement information.

Our challenge (upheld) was based on expert testimony from radiology technicians. They testified that static measurements don’t determine the issue. In practice very large patients are frequently positioned differently, with their arms held over their head, duct taped, etc. And, we excluded a psychiatrist’s testimony in the same case. He would have opined that our client was essentially starving himself to death, as opposed to suffering from the effects of an undiagnosed stomach abscess. The psychiatrist was piecing together remote history, and attempting to diagnose a personality disorder from prior medical history.

However (as found by the Court) the psychiatrist failed to provide sufficient basis as to why our client met several of the required clinical findings to support that personality disorder diagnosis  –or to adequately explain how such a disorder would essentially lead to a suicidal course of behavior. And, the Court was also persuaded by the defense experts failure to consider alternative (physical) explanations for the patient’s course.

All in all, Daubert challenges remain a robust feature of Federal practice. And, though the related “Frye” doctrine is occasionally applied in New York malpractice cases, it tends not to be a regular feature of New York malpractice cases. In practice most New York malpractice Judges can be persuaded (unless testimony is truly “off the charts”) to defer to the Jury’s evaluation of expert reliability.

Laurence DeutschNorth & Deutsch LLP 


Daubert Challenge Abigail WilliamsExperts are generally vulnerable to a Daubert challenge when the opinion that they are giving is not supported by the generally accepted medical literature. Or if they are applying the science to their opinion in a way that is not generally accepted. As science and technology change it is reasonable that opinions will change. However, these opinions must be supported by the majority position in the scientific literature and applied in a rational and scientific manner.

I once had a trial in which we claimed that the Plaintiff died from a heart attack. Our expert was well qualified, and based his opinion on generally accepted literature. The expert for the defense wanted to testify that although all of the testing and symptoms pointed to the fact that this was a heart attack, in reality, it was something else….. he did not know what the something else was, but it was not a heart attack. Although we argued Daubert, the judge in that case thought that the defense experts opinion could come in as “his opinion” and the lack of support in the literature was folly for cross.

The most important way to prevent a Daubert challenge against your own expert is to make sure that you are familiar with the relevant scientific literature that he or she is relying upon. Make sure that his/her opinion reflects that body of literature. If your expert’s position is that the body of scientific literature does not apply to any given case then he/she must identify specifically why it does not apply and why their opinion goes against what is generally accepted.

Abigail WilliamsAbigail Williams & Associates, PC


Daubert Challenge Bruce Feder I was involved in an analogue drug prosecution case where the defense challenged the DEA experts and the government challenged our experts in 2013.

You must select qualified experts whose opinions have support in the relevant scientific community. “Outlier” experts and topics are more likely to attract Daubert challenges. If the expert ‘that wrote the book’ on the topic is selected, there will be less susceptibility. However, if a ‘courier profiles’ expert can be admissible, it seems any expert should be allowed. In my case, the Court allowed ‘users’ to testify that an illegal drug had similar stimulating effects to the analogue drug. Daubert seemingly has the same weakness of subjectivity as the old Frye tests.

Bruce FederFeder Law Office, P.A. 


Daubert Challenge Rudy RobinsonI have been subject to numerous Daubert challenges during my 42-years of practice and have survived all but one. The only one that I did not survive was due to the fact that the judge ruled my report, as well as the other party’s expert report and opinions were irrelevant to the damages/losses incurred by the plaintiff in a breach of contract case.

I have learned many things from these challenges. Every report I write after a challenge is that much better or improved from my experiences. Specifically, I have learned it is a must to address each issue or allegation upon which the motion to strike is based by providing additional information, published articles or treatises that sustain my methodologies or analyses of the data or refocusing on the evidence of facts of the instant case that I have relied upon that clarify any and all incorrect or misleading information provided by the opposing counsel.

It is vital to address any and all inherent weaknesses in your report or opinion by facing them head on in the development stage of your work by talking with your client’s counsel; citing more articles in support of any controversial or unusual methodologies or application of those methodologies. Be careful not to blindly adopt any assumptions or opinions of any experts that you may be relying upon by communicating with the expert in advance of publishing your report, challenging the underlying expert report or opinion by consulting with client’s counsel about the necessities of addressing challengeable areas. I have even retained an expert in this same field to review any underlying expert opinions for reasonableness, rates of error, analytical gaps, etc. (particularly when there is an opposing expert with similar credentials with dramatically different opinions).

Be sure and ask if there is a theme of the case. Discuss in advance with the counsel for the client what he or she thinks are the most important strengths and weaknesses of your opinions relative to the theme. Be familiar with the opposing expert’s opinions. Be prepared to address areas of weaknesses in that expert’s report or opinion. Ask questions about the reputation, prejudices and mannerisms of the judge, jurors, opposing experts, etc.

Rudy RobinsonAustin Valuation Consultants


Daubert Challenge Tim Wright Like most expert witnesses – I have had my findings and testimony questioned in court.

I think finding out what the court adheres to helps in preparation. From what I understand, some courts/judges still use the Frye standard or even the older pre 2011 Daubert standards. If there is any uncertainty, have the expert bring/submit peer-reviewed material and/or technical reports (several at least) that back up his or her claims. This may be difficult if their field of expertise is very new. However, there are almost always a few publications out there on new technology, procedures, and equipment. The only time this would be difficult is if the expert is one of the pioneers of that technology or procedure.

As a researcher, I always know to cite my findings – even if they are based on new scientific knowledge. If instrumentation is involved, I obtain spec sheets for each instrument and if the data are collected by someone else (usually a university, municipality, or other government entity) I obtain the maintenance and calibration records – if available. I bring this philosophy into the courtroom and it pays off when I am asked if I have any peer-reviewed or instrument specification material to back up my testimony. This is because I treat every case in which I am involved as a research project I would be comfortable having peer reviewed and published.

A colleague of mine, who is also an expert witness meteorologist, had his testimony thrown out by a judge – who cited Daubert. My colleague presented rainfall data, which was required in a lawsuit involving flood damage. The rainfall was reported to be higher in elevated mountainous areas. When the judge questioned as to why this was the case, he pointed out the proven scientific theory in meteorology of orographics. Rainfall is higher in elevated areas because as humid air is forced over hills and mountains, it cools, and by the Laws of thermodynamics and the Ideal Gas Law, condenses more rain out of the atmosphere than at lower elevations.

The judge inquired as to where he obtained this knowledge. He replied the theories were in place at least since the 1920’s and have been proven, peer-reviewed, and published in many articles and textbooks since (now “laws” instead of “theories”). The judge asked if he had “ALL OF” those published materials on hand. He said: “No, it would be thousands upon thousands of pages – and it is common knowledge in the meteorological community, as well as and part of my training and expertise to know these facts.”. The judge threw out his testimony. He could not demonstrate right there, in front of the court – besides his word – that that scientific knowledge was proven.

The rainfall data were also thrown out – even though they proved that more rain fell in the mountainous areas. Because of this, the judge also threw out the expert witness hydrologist’s testimony. That included the volume of water that would have passed through the river that caused the flooding. This is because the hydrologist’s calculations were based on the rainfall data obtained by and analyses conducted by my colleague.

This trial occurred before the amending of rule 702 (in 2000 and again in 2011 ). We both agreed that if the trial had occurred after those amendments, and the court adhered to the 2011 version, his testimony may not have been thrown out. However, I think choice of words or line of questioning by either attorney or the judge – or responses by my colleague – could have also contributed to the outcome.

I did hear that the judge in question was the target of many complaints and commonly had decisions like that appealed.

Timothy WrightAssociated Science Experts, LLC 


Leave a Reply

Your email address will not be published.

I am an