Sep. 28 2022

Quackery and Junk Science: What It Is, Why It Matters and How To Spot It

“I know it is common to speak of the ‘good old days’ of snake oil and soothing syrup as though they were gone forever. The amazing fact is that to a very great extent those good old days, so-called, are still with us.” – Commissioner George P. Larrick, Food and Drug Administration, 1955.

Quackery has been around since civilized society began. The term “quack” is often used to describe a person who misrepre­sents the physical condition of his patient, the reasonableness or efficacy of his “med­ical” treatment, or his education, train­ing, and skill in diagnosing and treating the medical condition at issue. (Quackery in California, 11 STAN. L. REV. 265, 267 (1959)). Similarly, a device, drug or treat­ment may be deemed a “quack” remedy when it is detrimental to one’s health or has no proven value for treating or cur­ing the condition at issue. (Id. at 296, n. 4). While “quack” conjures up images of shady peddlers and salesmen, spotting a quack is not always as easy as you may think. “Many common treatments exist in that disconcertingly large, messy grey zone between overt quackery and proven, uncontroversial medicine.” (P. Ingraham, Pseudo- Quackery in the Treatment of Pain (2021)). Oftentimes pseudo-quackery is recommended to patients under the guise of a “promising” or “up-and-coming” a treatment in a manner that leads patients to believe the treatment is already proven to work. (Id.) The idea of a “promising” treat­ment is sold by smooth and persuasive talk­ers who tout their “significant experience” and offer those desperate for relief (and a little sympathy) a dose of hope and reas­surance that their pain will miraculously disappear. (W. H. Gordon, M.D., Why Peo­ple Go to Quacks (1966), p. 45); J. H. Young, Ph.D., Why Quackery Persists (2001)).

Quackery Then and Now

Quackery “began when the first knave met the first fool.” (A Historian’s View of Quackery in 1974 (2016)). Colonial Amer­ica was certainly a breeding ground for quackery. (Id.) Nicholas Knopp, who immi­grated from England in 1630, concocted the “cure to scurvy” that was really just water “of no worth nor value” sold at a very high price to the gullible. (Id.; The Myths and Mysteries and Hunt for Nicholas Knapp (2017)). Throughout the 1800’s, German immigrant William Radam sold “Microbe Killer” which, according to Radam and the glass bottle it came in, cured all diseases. (Id.) However, like Knopp’s “snake oil” con­coction, Microbe Killer was nothing more than a diluted solution of sulfuric acid and red wine that, when taken in large quanti­ties, was actually poisonous (Id.) Despite the advancements and regulation in med­icine, quackery is still prevalent and looks strikingly similar to the “cures” sold by Knopp and Radam.

Today, quackery looks like the “Mira­cle Mineral Solution” (really just indus­trial-strength bleach) marketed as a cure for HIV, malaria, and Covid-19 and the patently false promise made by Theranos regarding the ability of its “technology” to perform 240 blood diagnostic tests with only one single drop of blood. The reason for this? Just as it was in Colonial Amer­ica, “there is a great deal of money to be made making false medical claims to peo­ple desperate for relief or a cure.” (Quackery Then and Now, As long as there is a monetary incentive, the push for “quack” medicines, treatments and devices will continue into the future.

Quackery Leads to Junk Science in the Courtroom

While quackery involves misrepresenta­tions as to the patient’s condition and/or the effectiveness of recommended treat­ment, “junk science” refers to the use of “scientific” evidence or testimony that is the result of questionable methodologies used to reach unsupported conclusions. (Gutheil & Bursztajn, Attorney Abuses of Daubert Hearings: Junk Science, Junk Law, or Just Plain Obstruction? 33 J. AM. ACAD. PSYCHIATRY L. 1150 (2005); N. Prefon-taine, Talcum Powder and Expert Power: Admissibility Standards of Scientific Testi­mony, 59 JURIMETRICS 341, 351 (2019)). Naturally, quack medicine and treatment leads to junk science in the courtroom, oftentimes in the form of unsupported causation opinions and unsupported con­clusions as to the condition of the plain­tiff, the “necessary” treatment, and the efficacy of such treatment. At its core, the battle over junk science in the courtroom “is ultimately intended to prevent fraud on society and the legal system” as there “is hardly anything, not palpably absurd on its face, that cannot be proven by some so-called experts.” (Chaulk v. Volkswagen of Am., Inc., 808 F.2d 639, 644 (7th Cir. 1986); D. Thornburg, Junk Science – The Lawyer’s Ethical Responsibilities, 25 FORDHAM URB. L.J., 449, 452 (1998); H.P. Sorett, Junk Science in the States: The Battle Lines, ATL. LEGAL FOUND. (2000), at p. 31)).

Any discussion regarding “junk sci­ence” naturally involves the U.S. Supreme Court’s decision in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), and its progeny. In Daubert, the “Court focused upon the admissibility of scien­tific expert testimony [and] pointed out that such testimony is admissible only if it is both relevant and reliable.” (Id. at 589). While Daubert demands that judges act as gatekeepers tasked with preventing pseudo or “junk science” from infiltrating courtrooms, judges must first be educated on what constitutes science and a reliable methodology. One major flaw of Daubert and its progeny lies in the fact that it leaves judges, who are “generally unversed in, and even adverse to, the sciences, with­out clear guidance or ample criteria upon which to predicate their decisions.” (B. Bil-lauer, Admissibility of Scientific Evidence Under Daubert: The Fatal Flaws of “Fal-sifiability’ and “Falsification”, 22 B.U. J. SCI. & TECH. L. 21, 24 (2016)). Judge Pos­ner expressed serious concern about the lack of scientific literacy displayed among judges and lawyers, emphasizing that such a lapse in knowledge and understanding “is worth notice because it is indicative of a widespread, and increasingly troublesome, discomfort among lawyers and judges con­fronted by a scientific or other technologi­cal issue.” (Jackson v. Pollion, 733 F.3d 786, 787 (7th Cir. 2013)).

Ultimately, Daubert places a heavy bur­den on judges and lawyers to understand and effectively and coherently translate sci­entific knowledge in a way that lends value to the understanding or resolution of legal disputes. As you can imagine, this lack of scientific sophistication can lead to unreli­able expert evidence and testimony mak­ing its way into the courtroom despite the “protections” of Daubert.

Unlike litigation or trial, science centers on objective facts that are not the result of a single theory or result. (Peter Huber, Junk Science in the Courtroom, 26 Val. U. L. Rev. 723, 741 (1992)). Science “is a process of replication and verification, a search for consensus.” (Id.) As Peter Huber explained,

[T]he only reliable test for objectivity in science “is to determine what many different people can see in common, from different van­tage points, in their waking hours. What individuals see alone, awake or in their dreams, is not science. A solitary white coat, test tube and resume are not science. Modern sci­ence is not a solitary undertaking.

(Id.) In contrast, “the courtroom setting is discrete, insular, and closed – a one-shot decision.” (Id. at 742-43). A “great para­dox of modern liability science [is that,] in attempting to control quackery outside the courtroom, we invite quacks to the witness stand.” (Id.). The reason quacks get invited into the courtroom is due to the complete lack of education and understanding of the methods of actual science, which are fun­damentally different from those required in litigation. (Id.). Allowing quacks to offer “scientific” opinions under the guise that they are supported by the medical commu­nity inevitably results in scientific anarchy that infects the legal system’s perception of science as a whole.

The only way to stop this deteriorating progression is for judges to “rediscovery rules of evidence consonant with the essen­tial collegiality of modern science.” (Id.). The rules necessary to execute this goal may not be self-evident, cannot be imple­mented mechanically, and will not work as intended if jurors do not understand and respect science. However daunting this task may seem, judges and lawyers need to remember that “[w]hatever his credentials, publications or affiliations, a scientist who becomes the alter ego of a lawyer is no lon­ger a scientist.” (Id.).

Confusion Over the Methodologies Supporting a Causation Opinion

In addition to the legal profession’s inept­ness when it comes to science, lawyers and judges lack a basic understanding of the methodologies associated with (and the proper application of) a differential diag­nosis and a differential etiology. Confused? You’re definitely not alone.

Differential diagnosis is the method by which a doctor determines what dis­ease or condition is causing the patient’s symptoms, which is determined by con­sidering “all relevant potential causes of the symptoms and then eliminating alter­native causes based on a physical exami­nation, clinical tests and a thorough case history.” (A. Hopp, Differential Diagno­sis and Daubert: Preventing the Misuse of Differential Etiology to Prove Causation in Toxic Tort Cases, 84 DEF. COUNS. J. 1, 6 (2017)). In contrast, differential etiology “is a causation-determining methodology” used by a physician to determine the exter­nal cause of the condition, which is done by “ruling in” and “ruling out” potential causes of that condition before arriving at a final conclusion as to the cause. (Id. at 7). “In short, differential diagnosis is the act of distinguishing one disease from another to select a proper treatment,” while differen­tial etiology is used to determine the cause or causes of such condition, most often for litigation purposes. (Id.; see also Hig­gins v. Koch Dev. Corp., 794 F.3d 697 (7th Cir. 2015) (“‘Differential diagnosis actually refers to a method of diagnosing an ailment, not determining its cause.”); M. B. Kent, Jr., Daubert, Doctors and Differen­tial Diagnosis: Treating Medical Causation Testimony As Evidence an Assessment of Admissibility Is Not the Same As an Assess­ment of Sufficiency, but Daubert Has Cre­ated That Confusion, 66 DEF. COUNS. J. 525, 527 (1999)).

While differential diagnosis and differ­ential etiology may seem quite similar, the differences are actually quite profound. (S. Spechler, Physicians at the Gates of Daubert: A Look at the Admissibility of Differential Diagnosis Testimony to Show External Cau­sation in Toxic Tort Litigation, 26 Rev. Litig. 739, 744 (2007)). “The ability to diagnose medical conditions is not remotely the same . . . as the ability to deduce . . . in a scientifically reliable manner the causes of those medical conditions.” (Tamraz, 620 F.3d at 673). Although doctors are taught how to perform a differential diagnosis and regularly do so in practice, there is very little training (if any at all) regard­ing differential etiology. (Id.) In most clin­ical settings, a physician only focuses on ” capable of producing a particular condition for purposes of recommending a course of treatment. (Sanders, et al., Dif­ferential Etiology: Inferring Specific Causa­tion in the Law from Group Data in Science, 63 UNIV. OF HASTINGS 851, 858 (2011)). For example, an ER surgeon does not need to know that the defendant driver caused a significant collision with the patient’s vehicle because he was intoxicated (i.e., he does not need to consider external causes of the patient’s post-collision condition), but he does need to consider the symptoms or complaints associated with the result­ing injuries, the location and condition of the injuries, and the patient’s physical con­dition (heart rate, blood pressure, etc.) to diagnose the specific injuries and identify the best treatment for the injuries. In con­trast, knowing whether the defendant’s act of driving drunk proximately caused the accident is key to establishing the defendant’s liability for the resulting injuries and damages.

The lack of sophistication in the legal profession regarding science and scientific methodologies has led to countless judicial opinions that conflate differential diagnosis with differential etiology.

Oftentimes this results in a finding that a physician’s causation opinion is sound and reliable when, in reality, the opinion is based on nothing more than patient his­tory and a physical examination. (Orga­nized Common Sense, supra, at p. 441). The confusion as to these different meth­odologies may lie in the fact that both require the doctor to “rule in” and “rule out” various possible “causes.” However, the “critical distinction is that, in the clin­ical setting, ‘cause’ means diagnosis, while in the legal setting ‘cause’ means a proxi­mate cause.” (A. Hopp, Differential Diag­nosis and Daubert: Preventing the Misuse of Differential Etiology to Prove Causa­tion in Toxic Tort Cases, 84 DEF. COUNS. J. 1, 12 (2017) (emphasis added)). Failing to understand this distinction inevitably leads to reliance on “a crude imitation of science, the unpublished hunch, the letter to the editor, the impressionistic ‘mosaic theory,’ in which the lawyer’s science of harmonious coupling substitutes for sys­tematic observation and analysis.” (Huber, supra, at p. 744).

Deciphering Legitimate Scientific Opinions from Junk Science Based on Quackery

Although most courts regularly confuse differential diagnosis with differential etiology when considering the reliabil­ity of a causation opinion, some courts have acknowledged the difference in these methodologies and criticized those “experts” who rely on differential diagno­sis to support causation. For example, the Sixth Circuit in Tamraz v. Lincoln Elec­tric Co. excluded an expert’s opinion that attempted to “elide the distinction between [plaintiff’s] disease and what caused it,” and emphasized that use of “diagnosis” and “etiology” interchangeably has allowed non-scientific opinions to make their way into the courtroom. (620 F.3d 665, 672-73 (6th Cir. 2010)). As the court explained, reliance on differential diagnosis “serves well in the clinic but not in the courtroom, where decision requires not just an edu­cated hunch but at least a preponderance of the evidence.” (Id. at 673). The court also observed that calling something a “dif­ferential diagnosis” does not satisfy the Daubert reliability question, but instead raises the following additional questions:

  1. Whether the expert made an accurate diagnosis of the nature of the condition,
  2. Whether the expert reliably ruled in the possible causes of that condition, and (3) whether the expert reliably ruled out the rejected causes. (Id. at 674). Similarly, the court in Pluck v. BP Oil Pipeline Co. found an expert’s opinion regarding the cause of the plaintiff’s disease unreliable because the exert did not rule out alternative causes and failed to identify his method for dis­counting other possible causes. (640 F.3d 671, 679-80 (6th Cir. 2011)). Likewise, the court in Chapman v. Proctor & Gamble Distribution, LLC rejected as unreliable an expert’s causation opinion due to the expert’s failure to address several other alternative causes and failure to explain why he excluded the other causes. (766 F.3d 1296, 1309-10 (11th Cir. 2014)).

In Magbegor v. Triplette, the plaintiff’s orthopedic surgeon, Dr. Langer, opined that the motor vehicle accident at issue caused the plaintiff’s shoulder injury because he did not observe any character­istics indicative of a chronic injury (which he defined as one or two years old). (212 F. Supp. 3d 1317, 1327 (N.D. Ga. 2016)). The court concluded that Dr. Langer’s opin­ion failed to satisfy any of the standards set forth in Daubert. (Id.) Specifically, the court emphasized the lack of evidence sup­porting the central premises of his opin­ion (i.e., that chronic shoulder injuries exhibit certain characteristics that were not observed in the clinical setting), nor was their evidence that the lack of these alleged characteristics reasonably led to the conclusion that the injury was chronic in nature. (Id.) More troublesome was the fact that Dr. Langer completely failed to account for any alternative causes despite his acknowledgment that pre-accident medical records showed prior complaints of shoulder pain with associated treatment and a long history of excessive use of the shoulder at issue. (Id. at 1328). Based on the foregoing, a lack of evidence that Dr. Langer’s opinion was accepted by the med­ical community and his complete failure to conduct any independent inquiry into the accident (the speed of the vehicles, the force of the impact, the location of the impact, the direction plaintiff’s body moved in response to the impact, or the position of the plaintiff inside the vehicle at the time of the impact), the court found his opinion unreliable despite his performance of a dif­ferential diagnosis. (Id.)

However, a differential etiology may not always be required. As a Georgia court explained,

A few examples of typical cases include: the brittle-boned octogenarian who falls in the kitchen and breaks her hip; the defensive end who has his knee crushed by a 330–pound offense tackle and suffers an anterior cruciate tear; the woman who falls in a grocery store and suffers a fracture of her wrist; and the unbelted passenger who is ejected during a car wreck, lands on his head in a cotton field and suffers a compression fracture of his cervical vertebra. In these typical cases, an orthopedist legitimately can adopt a patient’s history as his causation opinion, since the patient has sus­tained a common injury in a way that it commonly occurs.

(Bowers v. Norfolk S. Corp., 537 F. Supp. 2d 1343, 1359 (M.D. Ga. 2007)). In con­trast, complex injury cases involving mul­tiple possible causes or sources of impact/ trauma and relevant pre- accident or post-accident incidents, injuries or conditions require more than a clinical differential diagnosis. (Id.)

Take, for example, a plaintiff with inju­ries to her lumbar spine that allegedly began after a train ride and evidence of a prior, recent history of low back pain and treatment. In such a case, an orthopedist’s opinion that the vibrations from the train ride caused the plaintiff’s injuries and pain will not meet the Daubert standards when the opinion is based solely on the patient history, a physical examination, and a review of studies and radiographs. (Id.) This is especially true if the orthopedist fails to consider and rule out other possible causes for her back pain (such as pre- exist­ing causes), fails to explain why the vibra­tions of the train solely caused her injury, has no knowledge of the strength of these alleged vibrations and fails to explain how the vibrations could have caused (and did in fact cause) either a new low back injury or exacerbated her pre-existing condition. (Id. at 1356).


Any scientifically sound opinion as to the cause of an injury or condition will always be based on the methodical observation of many patients or test subjects, not on one physician’s impressions developed solely in the course of his clinical treatment of the plaintiff. (Huber, supra, at p. 746). The skills necessary to diagnose an injury and recommend a course of treatment are not the same skills required to determine the cause of the condition in question. (Id.) “The difference between the clinician and the scientist is one that courts must learn to the understand and affirm.” (Id.) To do this, we need to remember why we seek the opinions of physicians in the first place. While some would argue that a physician is called to testify solely to support the plaintiff’s injury claim or the defendant’s defense, a physician who testifies with only that goal in mind is not a scientist capable of offering reliable scientific opinions.

Attorneys and judges must remember that we seek the opinions of physicians in personal injury cases to assist in under­standing how the particular facts and cir­cumstances of the case establish causation and that the causation opinion offered is recognized and understood by science and the medical community as a whole. If this were not the purpose, then could we not just rely on injured plaintiffs to offer spec­ulative testimony that the accident caused their injuries? Sure, a speculative causation opinion based on nothing more than clin­ical observations and the physician’s clin­ical experience often persuade defendants to fork over large sums of money before trial or convince a jury to award large damages to the plaintiff. But such idio­syncratic speculation is not in any way anchored in broad-based objective science and standards and, in reality, does noth­ing more than turn the physician into “just another lawyer, masquerading as a pundit.” (Id.) And any doctor who engages in such quackery, resulting in the introduction of junk science, is in direct violation of their duty to ensure that they do not become an advocate in a legal proceeding. (Id. at 750).

Real science, as opposed to junk science, results in scientific facts or statements that can be proven true or false only after a finite, circumscribed inquiry. (Id. at 752­53). Real science is not an opinion cloaked in “mays,” “mights,” or “possibilities.” (Id. at 753). As Huber explained, the “language of could, possibly, may, might, and maybe that so often litters fringe testimony in court is not the language of science. Nor is science a business of completely open-ended speculation, where any idea can be floated but none can ever be finally brought back to earth.” (Id.). Anyone offering such a promise or opinion must not be confused with a real scientist capable of provid­ing a reliable scientific opinion, as science has limits that real scientists respect and acknowledge. (Id. at 753-54).

In an effort to eradicate junk science in the courtroom and keep quacks from falsely touting themselves as “experts” before a jury, defense lawyers need to fully understand the difference between medi­cal causation and legal causation and the scientific methodologies used to establish the same. Once these differences are under­stood, defense lawyers need to explain these differences to the court and oppos­ing counsel each time they get the chance. As history has proven, it is not safe to assume that judges or lawyers understand science, the differences between differen­tial diagnosis and differential etiology, or which methodology to apply. Only after lawyers and judges are properly educated as to these scientific issues can we expect to have any chance of ridding the legal sys­tem of the rife injustice that is continually perpetuated by an “expert” with a medi­cal degree and nothing more than a spec­ulative, narrow-minded, and unscientific opinion. Until this is accomplished, “what passes for science in court won’t be.” (Id. at 753).

Reprinted with permission of the Defense Research Institute (DRI).


Melody Kiella is an attorney in MGC’s Atlanta office. Her practice focuses on complex civil litigation, including trucking/transportation law, catastrophic personal injury defense, premises liability and negligent security. As an active member of the Defense Research Institute (DRI), Melody serves as the Online Programming Chair, and has previously served as the 2021 Trucking Law Primer Vice Chair for DRI’s Trucking Law Committee and the Publications Chair for “DRI for Life.” She is the 2022 recipient of the DRI Tom Segalla Excellence in Education Award, which honors a member whose contributions through legal scholarship exemplify the highest educational standards of DRI and further its mission of improving the skills of the defense practitioner. Melody is also a member of the Georgia Defense Lawyers Association, American Bar Association, Federation of Defense and Corporate Counsel and State Bar of Georgia.

Melody Kiella co-authored this article with David Wilson, an attorney with Gaines, Gault Hendrix, PC in Birmingham, Alabama.

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