Shannon Brown appeals the dismissal of his lawsuit against the Burlington Northern Santa Fe Railway Company (“BNSF”), which he filed under the Federal Employers’ Liability Act (“FELA”), 45 U.S.C. § 51 et seq. The sole issue he disputes on appeal is the district court’s 1 decision to exclude the testimony of his expert witness, David Fletcher, M.D. We conclude that the district court did not abuse its discretion and therefore affirm its grant of summary judgment.
I. Background
At the time of this appeal, Brown was a 36-year-old man residing in Knoxville, Illinois. He began his employment with BNSF in 1996 as a member of the Maintenance of Way Department. From 2006 to 2009 he progressed through a variety of job duties as a foreman, track inspector, and machine operator. In 2007 a family physician diagnosed Brown with carpal tunnel syndrome in both wrists and cubital tunnel syndrome in his left elbow.
2
On October 25 of that year, Brown allegedly injured his right shoulder after lifting heavy angle bars at work.
3
He reported
The day following his official return date, however, Brown had surgery on his right wrist to relieve his carpal tunnel syndrome. Surgery on the other wrist followed on January 22, 2008. He returned to work on March 24 without any restrictions. He had surgery on his left elbow in October of 2009 to treat his cubi-tal tunnel syndrome, and he was cleared to return to work on January 4, 2010. Brown’s surgeon for both of his wrist surgeries and his elbow surgery informed him that all three procedures were successful and resolved his symptoms. Brown would remain employed at BNSF without medical restriction until September 28, 2011, at which point he no longer worked at the company.
Before returning from his elbow surgery in 2009, Brown sued BNSF under FELA, alleging that the railway negligently caused cumulative trauma to his wrists, elbow, and shoulder. According to Brown, his duties at the railroad required him to use vibrating tools that either caused or aggravated his wrist conditions. He further alleges that, in September of 2009, he was required to work excessive hours without proper equipment while BNSF was short-staffed; he maintains that this exertion triggered or exacerbated the cubital tunnel syndrome in his left elbow, prompting his surgery the next month.
Discovery commenced, and Brown retained Dr. Fletcher to examine him and provide expert medical testimony. Dr. Fletcher’s expertise in diagnosing railway work injuries and identifying their cause is unchallenged. He is licensed to practice medicine in Illinois, and is a full-time physician. He graduated from Rush Medical College in Chicago and holds a Master’s Degree in Public Health from the University of California, Berkeley. Dr. Fletcher is a Fellow of the American College of Occupational and Environmental Medicine and has been appointed Clinical Assistant Professor at the University of Illinois and Southern Illinois University. In 2012 he was one of two doctors chosen to serve on the Illinois Workers’ Compensation Commission. He is also the medical director of SafeWorks, Illinois, a private occupational health clinic. Starting in 1985 and continuing through his 2012 deposition, Dr. Fletcher occasionally served as an independent contractor with two railroad companies, the Norfolk Southern Corporation and the Canadian National Railway Company. In that capacity he treated work-related injuries and performed physicals, tested employees’ fitness for duty, and conducted some ergonomic evaluations. He has served as an expert witness in past FELA cases.
Dr. Fletcher eventually submitted four expert reports on Brown’s behalf, although the last was excluded as untimely in a ruling that Brown does not challenge. The first report discussed Brown’s medical records and his independent medical evaluation that Dr. Fletcher conducted on August 2, 2011. Dr. Fletcher reported that Brown had no history of smoking, diabetes, or other common health risk factors. He noted that Brown reported a needle-like sensation in the palms of both hands that was minimal and easy to ignore. Brown also told Dr. Fletcher that his shoulder was “97%” better and caused him no pain. Dr. Fletcher inquired as to Brown’s employment, and Brown told him that his job required him to lift 100 pounds
Dr. Fletcher’s first report also relayed the results of his physical examination of Brown. The report notes atrophy and loss of muscle strength in his left elbow. Dr. Fletcher conducted a Tinel’s test on the elbow, which revealed nerve irritation. An elbow compression test similarly uncovered signs of injury. Dr. Fletcher also indicated impingement of Brown’s right shoulder, but his report goes on to contradict that finding by reporting that “impingement signs were negative bilaterally.” The report states that an MRI would be necessary to reach a “formal diagnosis” of any shoulder injury, but it notes that Brown could not undergo that test because he had a pacemaker in his chest. Dr. Fletcher recommended an arthroscopic procedure to identify any problems, but no such surgery was performed. Brown has not pointed out any other test confirming an injury to his shoulder. Nevertheless, Dr. Fletcher attributed Brown’s wrist, elbow, and shoulder injuries to his work at BNSF.
Dr. Fletcher’s second report was an update on Brown’s progress, issued on January 3, 2012, after he had examined him a second time. Brown reported pins and needles in his left elbow and numbness in his left hand, and Dr. Fletcher concluded that he required another elbow surgery. He also stated that Brown “had incurred permanent loss” of function and required “[permanent job restrictions.” Again Dr. Fletcher attributed these medical problems to Brown’s job.
In his third report, dated February 27, 2012, Dr. Fletcher more closely examined the cause of Brown’s condition. After summarizing Brown’s health concerns, he stated that he suffered from a “cumulative trauma disorder” caused by his work on the railroad. Carpal tunnel syndrome and cubital tunnel syndrome are both examples of cumulative trauma disorder because they result from repeated applications of force over time rather than one discrete event. Dr. Fletcher stated that he came to this conclusion by the process of differential etiology. “[I]n a differential etiology, the doctor rules in all the potential causes of a patient’s ailment and then by systematically ruling out causes that would not apply to the patient, the physician arrives at what is the likely cause of the ailment.”
Myers v. Ill. Cent R.R. Co.,
As we have noted, to conduct his method of differential etiology, Dr. Fletcher’s third report states that he employed a “job site analysis,” which consists of “traveling to the literal worksite with the patient and reviewing his or her job duties; measuring frequency and force required for various job tasks; videotaping and photographing job task activities for further analysis”; identifying “variances in the written job description as compared to the actual duties performed; using scientific measuring tools, such as a Chatillon gauge, which constitutes an objective measure of force; assessing push/pull job function factors; and evaluating the level of force exertion required to perform a job task.” Through the job site analysis, Dr. Fletcher could “rule in” Brown’s railroad work as a cause of his injury.
BNSF deposed Dr. Fletcher, and his accounting of his etiological investigation in this case differed considerably from the typical methodology described in his reports. Instead of going to Brown’s work
Moreover, Fletcher’s report did not discuss a number of potential alternative causes for Brown’s ailment. During his deposition, Dr. Fletcher stated that he had been aware of some, but not all, of the relevant information surrounding these potential alternative causes. For example, Brown was a volunteer firefighter. Fletcher testified that he knew this but that he did not know how long Brown had worked as a firefighter. He never observed Brown’s volunteer work there or learned his job duties. Brown also had a family history of cumulative trauma disorder, which Dr. Fletcher recognized but discounted. Although the doctor acknowledged that the “higher the [individual’s body mass index or “BMI”] the more likely obesity could be an independent risk factor,” he dismissed this potential cause because Brown’s BMI was “[borderline” and he was not “morbidly obese.” Dr. Fletcher did know that Brown regularly rode a motorcycle during the relevant time period, but he did not know the frequency or duration of the rides, or the type of motorcycle he owned. He concluded that any effect from the motorcycle would be minor because, he stated, Brown spent considerably more time working than riding. Finally, although Dr. Fletcher reported that Brown had no history of smoking, Brown himself admitted in his deposition that he had quit smoking only two or three years earlier.
The district court excluded Dr. Fletcher’s reports and testimony under Federal Rules of Evidence 702 and 703. The court held that Dr. Fletcher’s methods were unreliable because he deviated substantially from the recognized scientific practices that he described in his reports. As to Brown’s shoulder, the district court doubted whether Brown had even sustained an injury because Dr. Fletcher had conceded that no formal diagnosis was possible without an MRI. More broadly, the district court reasoned that Dr. Fletcher was offering an ergonomic opinion as to the relation between Brown’s job duties and his injury, and that such opinions required a sound job site analysis of the type Dr. Fletcher mentions in his report. But because Dr. Fletcher never actually performed a job site analysis or observed Brown at work, his opinion lacked a reliable, testable basis. Moreover, Dr. Fletcher claimed that he was applying the method of differential etiology to “rule out” other potential causes, but the district court found that he failed to meaningfully consider or investigate several such possible risk factors for Brown’s condition, such as his motorcycle riding, volunteer firefighting, obesity, smoking, and family history of cumulative trauma disorders. In other words, Dr. Fletcher had failed both to “rule out” several possible causes and
Brown’s case for establishing his work conditions as a cause of his injury depended on Dr. Fletcher’s testimony, so the district court dismissed his FELA claim. This appeal followed.
II. Discussion
Congress enacted FELA in the first decade of the twentieth century in response to “the physical dangers of railroading that resulted in the death or maiming of thousands of workers every year.”
Consol Rail Corp. v. Gottshall,
The relaxed causation standard is simple enough to meet in cases involving readily understood injuries,
e.g.,
those that result from being hit by a train. “But when there is no obvious origin to an injury and it has multiple potential etiologies, expert testimony is necessary to establish causation.”
Myers,
A district court’s decision to exclude expert testimony is governed by Federal Rules of Evidence 702 and 703, as construed by the Supreme Court in
Daubert v. Merrell Dow Pharmaceuticals, Inc.,
Dr. Fletcher sought to offer a differential etiology in this case. “Differential diagnosis is an accepted and valid methodology for an expert to render an opinion about the identity of a specific ailment.”
Myers,
In reviewing the district court’s decision to exclude expert testimony, this court “first undertakes a
de novo
review of whether the district court properly followed the framework set forth in
Dau-bert
.... ”
United States v. Hall,
Brown first contends that the district court “exceeded the scope of its gatekeep-ing function” under Daubert by nitpicking Dr. Fletcher’s factual observations and gainsaying his conclusions — both of which are properly roles for the jury — rather than simply determining whether he used a reliable method. Appellant’s Br. at 36. Second, Brown argues that Dr. Fletcher did properly adhere to his method of differential etiology and that the district court abused its discretion in finding otherwise. We take both arguments in turn.
The district court properly understood the
Daubert
framework. It noted that “[t]he court’s role as gatekeeper is strictly limited to an examination of the expert’s methodology.”
Brown v. Burlington N. Santa Fe Ry. Co.,
No. 09-1380,
Although the district court did observe factual deficiencies in Dr. Fletcher’s reports, it clearly stated that it was excluding the doctor’s testimony because he failed to follow a reliable method; indeed, he deviated from his own stated description of a job site analysis and of differential etiology in general. Dr. Fletcher entirely failed to personally observe Brown’s working conditions, obtain a written work description, or perform scientific tests. He also failed to investigate several possible causes of Brown’s health problems. The factual deficiencies or discrepancies the district court identified are the result of Dr. Fletcher’s faulty methods and lack of investigation. The district court used the gaps in Dr. Fletcher’s analysis as illustrative examples of the perils inherent in applying subjective experience instead of a proper scientific approach. The district court did not exceed its role under Dau-bert.
Brown’s remaining argument is that the district court abused its discretion in finding that Dr. Fletcher failed to apply a reliable method. We have recognized that there is “nothing controversial” about using differential etiology to establish legal cause.
Schultz v. Akzo Nobel Paints, LLC,
The district court did not abuse its discretion in finding that Brown’s motorcycle riding and volunteer firefighting were obvious potential alternative causes for his injuries. The causal link Dr. Fletcher drew between Brown’s job and his injuries lay in the presence of vibratory and other types of equipment that can harm elbows, wrists, and shoulders over time. But the handlebars of a running motorcycle obviously vibrate, and firefighters must frequently struggle with heavy equipment. Brown is correct that under FELA he need only prove that BNSF’s negligence was a cause, not the sole cause, of his injury. But without performing an investigation, Dr. Fletcher could not rule out either activity as the sole cause of Brown’s condition. And although Brown’s weight, history of smoking, and family medical history were each not likely the sole cause of his ailments, these risk factors combined with either the volunteer firefighting or motorcycle riding (or both) could have been wholly responsible for Brown’s condi
Brown insists that Dr. Fletcher did consider these obvious alternative causes, but the record shows otherwise. The doctor disregarded Brown’s motorcycle riding as a factor because he assumed Brown worked for longer periods than he rode. But as BNSF rightly points out, the proper question is how long he rode the motorcycle as compared to how long he used vibratory or similarly taxing tools at work. And Dr. Fletcher could not possibly answer that question in a systematic, testable fashion because he did not know the duration and frequency of Brown’s motorcycle riding. Even worse, he did not know the duration or frequency of Brown’s exposure to vibrations at work. He did not have enough information to conclude that one value was higher than the other, or even to doubt that the former overwhelmingly exceeded the latter. Comparing two unknown, potentially wide-ranging variables is not a scientific exercise. There is no known error rate attached to such a calculation, nor is such guesswork widely accepted in the scientific community.
See Daubert,
Dr. Fletcher’s failure to consider Brown’s motorcycle riding and volunteer firefighting distinguishes this case from
Schultz,
Not only did Dr. Fletcher fail to investigate and systematically rule out two obvious potential causes, but it is not clear that he ruled out any serious alternative. It is true that Brown apparently does not have diabetes, which could be a risk factor. Dr. Fletcher also determined that Brown’s weight was not likely not a problem, because his BMI was “[bjorderline.” But even this is difficult to square with his observation during his deposition that “[t]he higher the BMI the more likely that obesity could be an independent risk factor” for carpal tunnel syndrome. He did not explain at all why this positive relationship would exist only for the “morbidly obese.” Brown’s weight could have made it more likely that his motorcycle riding or volunteer firefighting was solely responsible for his condition. Of course, we can only speculate because Dr. Fletcher did not adequately investigate this possibility.
As the district court correctly observed, Dr. Fletcher’s failure to rule out obvious potential causes was only half the problem. He also failed to reliably “rule in” Brown’s workplace activity as a potential cause of Brown’s condition. Dr. Fletcher failed to consider that Brown’s job duties changed
In response, Brown contends that precise measurements of the duration and frequency of his exposure to vibratory and other potentially damaging tools are unnecessary because no precise relationship between the frequency and duration of exposure and a particular cumulative trauma injury is known. Indeed, it likely varies from patient to patient. But because Brown was exposed to multiple sources of continued vibration and other trauma, Dr. Fletcher had to have some reliable basis for opining that Brown’s work activities played at least a small role in his injury. Data comparing the relative duration and frequency of exposure could have provided that basis; perhaps there were other ways. But Dr. Fletcher did not pursue any of them. Brown also argues that BNSF’s experts also did not perform frequency and duration tests of its equipment either, but pointing out deficiencies in the defendant’s expert testimony cannot help Brown, who bears the burden of proving negligence and demonstrating the reliability of his own expert.
Brown claims that Dr. Fletcher was prevented from conducting the type of job site analysis described in his reports because BNSF would not cooperate by, for example, allowing him to test its tools or providing him with a written job description. But that is a matter that should have been brought to the district court’s attention during discovery. A party cannot enter into evidence unhelpful expert testimony on the grounds that the other side made them do it. If Brown felt that BNSF was unreasonably constraining his expert’s investigation, he should have raised that issue and then, if unsuccessful, pressed it on appeal.
No one disputes that Brown’s injuries could have been caused by frequent or long-lasting vibrations, or that his job exposed him to a significant amount of vibration over the years. But if that were sufficient to establish causation, expert testimony would be unnecessary in this case. Any layman can understand that connection. Brown wishes to use Dr. Fletcher’s quarter-century of experience in the field to rule out other potential causes. But experience without reliable, testable methodology is not sufficient.
See Gen. Elec. Co. v. Joiner,
III. Conclusion
Because the district court did not abuse its discretion in excluding Dr. Fletcher’s expert testimony, its grant of summary judgment is Affirmed.
Notes
. The parties consented to a referral of this case to a magistrate judge, who excluded Brown’s proposed expert testimony and granted summary judgment. For simplicity we will refer to the judge as the district court.
. According to WebMD, "[cjarpal tunnel syndrome occurs when the median nerve is compressed because of swelling of the nerve or tendons or both.... When this nerve becomes impinged, or pinched, numbness, tingling, and sometimes pain of the affected fingers and hand may occur and radiate into the forearm.” At its most severe, the condition may result in "permanent deterioration of muscle tissue and loss of hand function.” Carpal Tunnel Syndrome, http://www.webmd. com/pain-management/carpal-tunnel/carpal-tunnel-syndrome (last visited Aug. 25, 2014). Similarly, "[cjubital tunnel syndrome ... is caused by increased pressure on the ulnar nerve, which passes close to the skin's surface in the area of the elbow commonly known as the ‘funny bone.’ ” Symptoms of cubital tunnel syndrome include "[pjain and numbness in the elbow,” "[tjingling, especially in the ring and little fingers,” "[wjeakness affecting the ring and little fingers,” and “[djecreased ability to pinch the thumb and little finger." Cubital and Radial Tunnel Syndrome, http:// www.webmd.com/pain-management/cubital-radial-tunnel-syndrome (last visited Aug. 25, 2014).
.Some disagreement persists in the record as to what exactly Brown claims to have been lifting when the alleged injury occurred, but that issue is irrelevant for our purposes.
