Licensed Professional Engineers

"Daubert is Dead - How Engineering Testimony Relates to the Daubert Ruling"

by Dr. L.D. Ryan


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Introduction. Safety Works:

   Humpty Dumpty went for a ride.

   Humpty Dumpty flipped and he died.

   Humpty’s family had such a terrible loss.

   Because of Daubert their expert was tossed.



Figure 1. Mr. Egg’s Demise on an ATV.


   The author starts this discussion looking briefly at safety issues and then moving into issues that retard the advancement to a safer world namely some of the engineering Daubert decisions.

   As will be shown, Daubert v. Merrell Dow Pharmaceuticals was a Supreme Court of the United States ruling that has been wrongly applied to engineering in many cases. This ruling allows manufacturers to continue selling dangerous products because judges do not allow plaintiff experts to testify based on Daubert. The trial judge tosses out the expert’s testimony when he or she thinks the expert did not use testing, peer review, error rate, standard procedures, and acceptance by the scientific community. It all sounds good, but some of it is pure unadulterated B.S.

   If there were a question in a survey that asked, “Are you for a safer world?” The answers would be 90% in favor and 10% against safety. The 10% represents the terrible ten that causes so much trouble in our world. If the question were asked, “Who is at fault in the ATV accident with Mr. Egg in Figure 1?” The response might be 75% blaming Mr. Egg, 15% blaming the ATV manufacturer, and the terrible ten blaming God who obviously punished Mr. Egg for hidden sins. With legitimate lawsuits, the plaintiff attorney’s battle is tough enough finding a fair jury pool without unfairly burdening the case with the misapplied Daubert ruling.

   The problem is cultural as far as our attitude about safety. We all know and believe that stupid people do stupid things. This includes trial judges, lawyers, and experts. Blaming the injured and the dead in accidents is easy. Stupid people do stupid things. Therefore, there is a strong suspicion that the person involved in the accident did something dumb. The problem is we need to accept the fact that we all do stupid things on occasion. Some of the things we do are foreseeable. This human trait will never change. Let us accept that fact and hire engineers who manufacture machines and products that follow the engineering code of ethics that states, “Protect the health, welfare, and safety of the public.”

   If safety works there should be evidence proving this point. The National Safety CouncilInjury Facts proves the point that we can live in a safer world. The death rate per 10,000 motor vehicles ranged from 33.38 in 1913 to 1.92 in 2004.

Figure 2. Death Rate per 10,000 Motor Vehicles from 1913-2004


   Safety works. Some people believe there is someone keeping track of our number and when our number is up it is up. Either the person keeping track of our number changes his or her mind with vehicle accidents, or safety works and we can keep people alive and well with good solid engineering.

   Attitude for safety showed up in a friend who had the idea that the seatbelt law was not constitutional or something. This person never wore his seatbelt because the government was not going to tell him that he had to wear a seatbelt. This guy is part of the terrible ten percent. He fell asleep driving. His son was with him. His son was thrown out of the vehicle, the following car drags the boy, and a helicopter flies to the nearest children’s hospital to save the child’s life. I stayed away from visiting this friend in the hospital because I knew I could not control my anger against him. To make matters worse, many in his church said it was good that the boy was not wearing a seatbelt because that saved the kid’s life.

   The courts are the last bastion to protect consumers from unreasonably dangerous and defectively designed products, machines, and structures. Daubert is not helping the author as an engineer to "Protect the health, welfare, and safety of the public."

   Personally, I have never seen the Daubert challenge applied to defense experts. The lower legs of stepladders buckle on certain manufacturers’ models. Their experts come to court, and lay a stepladder down on the floor. They drop a cement block on the horizontal stepladder front leg. The leg bends inward. Since it looks like the failed accident stepladder, they claim the plaintiff fell on the leg. The truth is that it is impossible using old scientific equations to fall on the stepladder because the falling climber hits the floor long before the ladder can get into a nice horizontal position. Tests using dummies produce the same result. This junk science has been the bulwark of stepladder defense experts, but I have never seen their testimony tossed with Daubert.

Daubert, et al. v. Merrell Dow Pharmaceuticals, Inc.

   Every practicing trial lawyer doing product liability knows about Daubert. Just in case there are readers who have been trapped on a desert island, there was a drug called Bendectin that pregnant women took for morning sickness. It was alleged to have caused birth defects. There were over one thousand lawsuits. One suit, Daubert, et. al. v. Merrell Dow Pharmaceuticals, Inc, changed the litigation world. The drug manufacturer went to the Supreme Court of the United States. There was a raging controversy over the drug Bendectin that followed on the heels of the drug Thalidomide, which did cause terrible birth defects. Merrel Dow was sued by the mother of Jason Daubert who was born in 1974 with only two fingers on his right hand and no lower bone on his right arm. His mother had taken the anti-nausea drug Bendectin. The Daubert ruling came out of the Supreme Court decision in 1993. There were experts for and against the drug. The judge’s decision was based on Frye v. United States where the expert’s testimony must be based on techniques generally accepted as reliable in the relevant scientific community.

   The testing of new drugs and the engineering of products are as different as night and day. The science used in drug manufacturing as it relates to the human body and the design of bridges and buildings are poles apart. Reaction of the human body to a drug cannot be compared to the design of machines and products. Engineering takes old science that has been put into a convenient form for general engineering use to apply repeatedly to different designs. Testing and rate of error are usually not part of the engineering process because the procedures are well known and constitute the standard of care by engineers. Engineers use equations to design things without testing, rate of error, peer review, and all the other things defendants claim should be done. How the Daubert ruling has been perverted to apply to standard engineering procedures is unbelievable. Daubert is now standing in the way of getting manufacturers to do what is normal and right from an engineering point of view because legitimate plaintiff experts are being denied the privilege of testifying.

   To kill Daubert as it relates to standard engineering requires knowledge of how engineering actually works.

How Engineering Works:

   Designing with equations: Hopefully, the liberal arts majors will not have a serious mental collapse when simple engineering equations are introduced. Total understanding of the equation is not necessary, but this fact must be understood, an equation can be used to design an element in a machine or a product without testing or peer review. Universities teach and practicing engineers use certain equations to design machines, products, and structures. With these design formulas, there is no need for testing. There is no need for peer review. There is no need to cite and follow some procedure. The error analysis does not apply. These universally accepted equations have been a vital part of the design process for hundreds of years. They are so universally accepted by the engineering community that all that is needed is to calculate the properties of the element using an equation.


   Assume someone wants to build a pedestrian bridge across a mote filled with alligators. Assume the bridge fails when a fat couple walks across, and both become part of the alligator’s food chain. The combined weight of the couple is 600 pounds. The bridge builder is sued. The plaintiff expert uses one equation to find the stress in the bridge beams. That equation is:



   This equation is found in ancient engineering textbooks and in modern engineering textbooks. The σ is the stress in the beam. The value of the failure stress is widely published in books. The “M” is the bending moment, and the equation for the bending moment is conveniently placed in engineering textbooks. The “z” is the section modulus, and it has been calculated and placed in steel manuals.

      The bending moment is calculated from the equation:


   The only discussion is the amount of weight on the beam. When people walk, they add more than their dead weight to the beam. It is foreseeable that other people could be on the bridge at the same time. The weight is the only debatable factor in the whole process. Yet the author has been asked if there was any error rate, peer review, and testing of this simple process. The problem lies in the fact that judges, lawyers, and juries are so ignorant of the engineering process, that the whole process of Daubert is in itself junk science gone crazy. Chief Justice William Rehnquist’s dissent in Daubert stated that many judges lacked scientific literacy to effectively fulfill their role as gatekeeper of scientific evidence.

   As engineers, we rarely do anything that requires peer review, testing, and rate of error analysis. The building that I am sitting in was never tested before it was built. Large high-rise building, bridges, towers, and other structure are not tested before being erected. There are code equations that many structural engineers follow in designing structures. The code equations can all be derived from the fundamentals, and the fundamentals are very old stuff. There is no need to test these proven equations. Sir Isaac Newton developed some of the equations in the 1700’s.

   Designing with mechanism analysis: Mechanism analysis is also old, and it has been applied for years by engineers. Mechanism analysis is a study of the movement of linkages, cams, and four bar mechanisms as an example. It is a graphic solution. I was once questioned on this with a particular mechanism. I was asked how I knew the mechanism would work without testing and peer review. I responded by saying it was like closing a door. The door swings on the hinges and goes from open to closed. I had a drawing showing how the mechanism worked. In the mind of the defense attorney, I had somehow invented some untried and scientifically unproven theory. The proof was in the drawing. Here is an example in Figure 3 where the link rotates 24.2838 degrees around pivot “C” and the lid rotates 6.9765 degrees around pivot “A”. A viable mechanism is proved from drawings. One part moves and the other follows. It is that simple, and it is all done off the drawing using computer aided drafting, CAD, software.


Figure 3. Mechanism for a Piano Bench Lid



   Designing from theory and not experience: I taught engineering for 22 years. Engineering education is not experience based. Engineering education is based on analytical tools for the elements in many products, structures, and machines. Lawyers should go to a college bookstore and buy an engineering design book by authors such as Spotts or Shigley and read the table of contents. Many defense attorneys try to get experts disqualified because the expert hasn’t designed an ATV or a stepladder. Without this experience, the expert is allegedly not capable of testifying. Nothing could be further from the truth. The old book titled Design of Machine Elements by M.F. Spotts illustrates the point of how engineering education is accomplished, which then is used in practice. The table of contents in Spotts’ book is produced in Figure 4.







Chapter Number

Contents of Chapter


Fundamental Principals


Working Stress








Belt, Clutches, Brakes, and Chains


Welded and Riveted Connections




Ball and Roller Bearings


Spur Gears


Bevel, Worm, and Helical Gears


Miscellaneous Machine Elements


Dimensioning and Detail


Engineering Materials

Figure 4. Table of Contents of "Design of Machine Elements".


   I have carried Spotts’ book to clients’ offices and used it to design a product or machine that had never been done before. Shown in Figure 5 is a machine co-designed by myself and Mr. Jim Mallory on a new project years ago to glue glass handles on a glass tumbler.

Figure 5. Invention of Mallory and Ryan


   Machines are designed by fundamental equations and not by experience with a specific machine. If experience was required with a family of products or machines, nothing new would ever be designed. There was no testing or peer review or any of the other Daubert generated concepts. Mallory and I simply designed and built the machine based on engineering concepts. It ran as designed.

   More recently, a manufacturer of tools for the oil and gas companies came me to design a tool so they could fix a meter riser value without shutting off the gas to the community. This is shown in Figure 6.

Figure 6. Miter Riser Shutoff Valve by the author.


   The design was completed using standard engineering tools. This design was new and had never been done before by the company or the author. There was no peer review. There were no standards to follow. Everything was within standard engineering component design except the rubber seal used to shut off the gas. This required testing because there were no engineering equations to predict the outcome. Shown in Figure 7 is the seal. The tests were successful when the engineers saw two seals develop in the clear tube.

Figure 7. Testing of the Rubber Seal

   There were no standard engineering equations that I could find that calculated how the rubber would swell when compressed on the end. With experimentation and testing, a rubber seal was designed that successfully created a double seal. Standards, for this test, do not exist. This is another perversion of the Daubert challenge. On the rare occasion when testing is required, the professional engineer must create a testing protocol. If the design is new, the testing will be new. On occasion, testing is required, but testing is not needed when the standard tools of engineering can be used.


The Fiction of Technical Peer Review:


   I wrote an article in the January 2003 issue of Trial magazine on this subject. Peer review has such a wholesome sound to it that a responsible expert or writer should investigate how this is done. We all would like to be peer reviewed to receive the blessings of engineers out there.

After researching the subject, I found formal peer review does not exist. I talked to Donna Hull, publication director of the American Society of Agricultural Engineers, ASAE. She told me that ASAE conference papers are not peer reviewed. Articles in their technical journals receive a small amount of scrutiny. The technical paper for inclusion in a technical journal goes to an area editor. The area editor sends it to two reviewers. The reviewers check the math and evaluate whether the material is new and makes sense, and they assess whether the author is aware of what is going on in the relevant field. Most other technical journals follow a similar procedure.

Three things came out of this study: Conference papers are not peer-reviewed; technical papers are reviewed by a couple of people; articles published in technical magazines must involve new material.

Engineering is old science applied to many different designs. Most of the old equation tools of engineering have been extensively peer reviewed because the designs prove the equations are valid. Your car runs so the gearing equations, bearing equations, roller chain equations, "v" belt equations, stress equations, and a zillion other equations work. Buildings and bridges prove that the structural equations used in engineering are correct. There is absolutely no need to peer review 90% of engineering testimony. What vehicle exists in our society that peer reviews old stuff? There is not any. No one can get old technology published for a peer-review.

The only thing that comes to mind with the word "peer-review" for engineering is to add it to the cussing list of words. The next time the hammer smashes the thumb use the new cuss word, "OH PEER-REVIEW!"


Test Protocol:


   When the expert does a test, the defense attorney follows with the next question. "Did you follow some standard protocol in the tests, or was this test peer reviewed." Engineers must design their own test when testing is needed. There is no place to run and find some laid out testing procedure for something new, and if there were someplace to find the appropriate tests, it is not necessarily needed. For example, in 1967 I was asked to find the center of gravity for a golf cart. There is an ASTM standard to find the center of gravity of a vehicle because finding the center of gravity of anything comes up frequently. The procedure was to lift the golf cart and use a transit to transfer a line from the hoisting cable down across the body of the golf cart. The line is drawn. Next the golf cart is suspended again, but at a different angle. The process is done two more times. The lines drawn on the side of the golf cart in an ideal world would cross at a point, which would be the center of gravity. In the real world, this does not happen. The result is a small triangle, and the center of gravity is somewhere inside the small triangle. That was one of the few times I followed a standard procedure because when finding the center of gravity of a heavy tractor, the procedure was not applicable. A crane large enough to pick the tractor up was not available. My test protocol followed very old engineering principles. The supporting weight of each wheel was found by driving the tractor on a large scale and recording the weight of each wheel. A forklift was available to tilt the tractor up to a point where it was ready to roll over. With this angle and the weight supported by each wheel, the center of gravity was found using ancient equations. This test protocol was as valid as the ASTM test.

Judges Decisions:


   Other Daubert Decisions: In a case called McKendall v.Crown Control Corp. a trial judge tossed out an expert who proposed a barrier on a forklift to protect operators from shifting loads. The court found the mechanical engineering expert’s testimony inadmissible because it was not based on scientific principles. This expert, with 50 years of experience, could not testify because of Daubert v. Merrell Dow Pharmaceutical on a barrier according to the trial judge. The Ninth Circuit reversed the decision of the district court under Rule 702. In the case of Compton v. Subaru of America, based on Rule 702,the court found the expert’s testimony concerning the feasibility of a safety device was based on the expert’s engineering experience. The testimony was factually helpful and relevant.

   The Daubert Decisions on LD Ryan: On almost every case now, I have a Daubert challenge to face. I do not know of any cases where my testimony was not allowed based on Daubert. Lately, I have been getting and reading the Daubert rulings and for this article a couple court rulings should be helpful. Some excerpts of two cases follows:

   Ireland v. Bauer Corporation: “Bauer objects to an experiment conducted by Dr. Ryan and argues that as a result of this experiment, Dr. Ryan should be completely precluded from testifying in this case. Dr. Ryan, in part, theorizes that the accident to Ireland occurred when the stepladder racked to the left and thereby became unstable. This aspect of Dr. Ryan’s testimony is based on the testimony of Ireland, Dr. Ryan’s observation of certain cracks in the fiberglass rails of the step ladder, and a test he performed utilizing a dummy. According to Ireland:


   The dummy test was conducted to provide a visual aid for the jury as to the scientific principles involved and to demonstrate what Dr. Ryan’s mathematical computations already proved – that it is impossible, as now claimed by Bauer, for Ireland to have fallen on the ladder thus causing the physical damage to the stepladder.


   Inasmuch as Ireland seemingly intends to utilize the dummy test as a demonstrative aid for the jury and not a recreation of reenactment of the accident, the strict evidentiary requirement of substantially similar circumstances no longer applies. McKnight by and through Ludwid v. Johnson Controls, 36 F.ed 1396, 1401 (8 th Cir. 1994). It is well settled that the only test for utilization of such a demonstrative aid for the jury is whether, the trier of fact will find it helpful and will not be unduly influenced thereby White Industries Inc. v. Cessna Aircraft Co., 611 F Supp. 1049, 1069 (W.D. Mo. 1985).


   Based on the record before the Court, Dr. Ryan will be permitted to testify about his racking theory and preliminarily at, may utilize the dummy test as demonstrative aid…


   Bauer argues that Dr. Ryan’s opinions should be excluded because Dr. Ryan has not ‘ruled out alternative explanations’ for the accident, arguing, for instance that Ireland ‘could have become dizzy and fallen off the stepladder or he could have slipped off the step on which he was standing.’ Bauer misconstrues the requirements of Daubert and FED R. CIV. P. 702. There is no requirement that an expert witness concoct a listing of every conceivable manner in which an accident may come about and then systematically rule out each possibility. To this end, the Eighth Circuit has noted that the requirement of the ability to rule out other explanations cannot be carried to quixotic extremes. Lauzon v. Senco Products, Inc., 270 F.2d 681, 693 (8 th Cir. 2001). In this case, Dr. Ryan’s theories, if believed by the jury, adequately rule out, by common sense implication, other reasonably possible theories of the accident, including human error. As observed by the Lauzon court:


   After discounting obvious alternatives through scientific testing, an expert need only be able to explain why other conceivable causes are excludable. The opposing party may attack the expert’s explanations on cross examination, thereby requiring the expert to offer valid explanations as to why his conclusion remains reliable.


   The Court likewise rejects Bauer’s contention that Dr. Ryan should be excluded from testifying because his theories have not been tested, nor published, nor subjected to peer review. Again, if believed by the jury, Dr. Ryan’s theories are based on long-established and generally accepted scientific theories. Such theories themselves have been tested, published, and subjected to peer review over the course of decades or longer.”


   Bryant v. United Container Machinery Group et. al.: In this Daubert hearing, I was there and questioned for the record. This hearing was done in the United States District Court for the Southern District of Mississippi Jackson Division before the Honorable William H. Barbour, Jr. Some of the Judge Barbour’s remarks are quoted next. These two rulings by Judge Maughmer, stated above, and Judge Barbour, stated next, should be carefully read. These two Federal Judges are saying there is a problem applying Daubert indiscriminately to engineering. I have underlined the important portions for a quick review by the reader in the next Daubert hearing.

   “The court has considered the motion, has heard the evidence and has considered the arguments of the defendant seeking to exclude the testimony of L. D. Ryan by way of a pretrial Daubert hearing.

   The court is well aware that it has a gatekeeping function. The court believes that this gatekeeping function is to to eliminate bogus expert witness from testifying in cases in general. The court understands the gatekeeping function to keep otherwise qualified experts in a particular field from testifying either outside of their field or within their field but without having done the proper foundation work to support that testimony.

   The court realizes and the court’s experience has been that mechanical engineers can, in many instances, be jacks of all trade, particularly in the context of retired college professors who make their living by testifying in products liability cases. The court personally takes the gatekeeping function seriously and has excluded the testimony of witnesses in the past who have testified too broadly for their expertise.

   In this particular case what we have is a relatively simple machine about which there is conflicting expert testimony as to its safety. …

   Essentially, because the law says that if a machine is said to be defective by an expert, the expert must then go on and testify as to a feasible alternative design; or if there is no feasible alternative design, then there must be warnings placed on the machine. That’s what the testimony of Mr. Ryan attempts to do.

   The defendants question his alternative designs; however, the designs that he proposes are simple. They are understandable to this court who is not an engineer. They, according to the witness, are based on general engineering principles. The witness has said for practical purposes it is usual for consulting mechanical engineers to design machines for application in which they have no experience. The court sees no reason to distrust or disbelieve that testimony.

   The court is not saying that a mechanical engineer may testify as to any mechanical engineering application. Certainly, there must be complications and needs of specific types of industries for very specialized knowledge; but that’s not the case here. Because of that the court thinks that Mr. Ryan has the knowledge and experience to design an alternative machine or alternative feeder to this machine that can work, should work, without being tested

   The Daubert factors of testing and peer review and acceptable rates of error and testing go to what Daubert basically reached. That was new science. The witness was sharp enough to say that was old science he was dealing with. The court, however, does believe that there is a difference in new science and old science and, accordingly, does not think that the Daubert factors really are applicable in this particular setting.

   The court has been convinced that this witness should be allowed to testify; that his testimony is based on his education, training and experience in the mechanical engineering field for a substantial period of time; that his designs were based upon calculations using formulas and other elements that are recognized in the mechanical engineering field and, therefore, have essentially already been subjected to peer review; and that the design he as stated are so simple that testing by actual making of a prototype machine is not necessary.

   …The court, however, is going to deny the motion in limine and will allow Mr. Ryan to testify. …”



   Engineering is the application of old science that has been peer reviewed. Testing is not necessary in most cases. The acceptable rates of error are not applicable. Following exact prescribed tests is not necessary when some new application is encountered. The old tools of engineering are used to design many differently named products, machines, and structures. A competent structural engineer can design a bridge, a tower, a high-rise building or any structural element regardless of the name. Graduate engineers are trained in the application of these old engineering tools that are used to design new products, machines, and structures. The engineer does not have to have experience to successfully design a specific product when old engineering equations can be used. Daubert relates more to new science. Engineering relates to old science. The proof of the validity of this old science used by engineers is in the products and machines in our society. If Daubert isn’t dead in mechanical engineering, Daubert is very sick and not expected to live. Plaintiff lawyers can help kill Daubert by presenting the real engineering story in the next Daubert hearing.

National Safety Council Injury Facts, 2005-2006 Edition Pages 110-111

Design of Machine Elements” by M F. Spotts, 6 th Edition, Page 19, Prentice Hall, Englewood Cliffs, NJ.

Design of Machine Elements” by M F. Spotts, 6 th Edition, Page 27, Prentice Hall, Englewood Cliffs, NJ.


Product Liability Law Reporter, November 1997

Ruling by John T. Maughmer, United State Magistrate Judge. United States District Court for the Western District of Missouri, Western Division. Ireland v. Bauer. Case Action No. 05-00091-CV-W-JTM

Daubert Hearing before the Honorable William H. Barbour, Jr., United States District Judge, November 18 th, 2002 Jackson, Mississippi. Dorothy Bryant and Closter Bryant vs. United Container Machinery Group et. al.


If you have any additional questions, or would like to discuss a potential case or current case that you are working on, please feel free to contact us via telephone at (479) 549-4860, email at, facsimile to (479) 524-4912, or land mail to Safety Engineering Resources, 22864 W. Spring Harbor Rd., Siloam Springs, AR 72761. Thank you for taking the time to review this informative article on Daubert and its implications to product liability law.