WORK A Journal of Prevention, Assessment .. Rehabilitation
ELSEVIER
Work 9 (1997) 295-297
Rehabilitation ergonomics
Witness: the truth please Dennis L. Hart a,*, Susan J. Isemhagen b , Leonard N. Matheson C a FOTO,
Knoxville, TN and Hart Ergonomic Consulting, Great Falls, VA, USA bIsemhagen Work Systems, Duluth, MN, USA C Washington University School of Medicine, Program in Occupational Therapy, St. Louis, MO, USA
While reviewing a deposition of an expert witness, it became evident that many of us follow different rules when we act as expert witnesses. But why the surprise? In the 'old days' (prior to 1993), we simply needed to have a 'heavy' curriculum vita and call ourselves an expert witness to be considered one on the stand; but what about the scientific principles of problem solving and the scientific principles of measurement? They should count, shouldn't they? Consider the Frye case (Fry vs. United States, 1923). This case is considered the case that 'articulated the now venerable rule of general acceptance' for forensic evidence. The pertinent part of the case focused on the thought process for accepting scientific evidence that emphasized the 'thing from which [a] deduction is made', rather than the way in which the deduction was made (Black, 1988). Over the years, courts have examined the bases from which evidence should be admitted; from facts or from deductive reasoning. Those decisions emphasizing the 'things' (i.e. following Fry) permitted thorough analyses of the facts, but the 'failure to focus on the question of reasoning and the standards of science can lead
*Corresponding author.
to less than adequate consideration of the scientific validity of expert opinions. Unfortunately, the alternative is the rejection of 'things' which according to Black (1988) may 'mean less judicial review of scientific evidence and more reliance of the adversary system to expose shortcomings to the jury'. Which ever approach a specific judge follows, 'decisions about the admissibility of scientific evidence will consistently accord with scientific reality only if courts look to the criteria and practice recognized by scientists. This holds true for medical as well as forensic science, but courts have been especially hesitant to examine the reasoning through which medical doctors reach their conclusions'. Simply supplant 'ergonomist' or 'therapist' for 'medical doctors' and you have the main point of this essay. The courts have deviated from scientific standards when accepting the opinions of physicians and ergonomists without demanding the scientific scrutiny of their thought process as well as the science of measurement concerning their facts. According to Black (1988) when the opinion of a medical expert is disputed, the courts typically look to the qualifications of the physician, 'the kind of facts upon which the opinion is based, and the certainty with which the opinion is expressed. The reasoning connecting facts to conclusions is
1051-9815/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved.
PII S1051-9815(97)00050-8
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D.L. Hart et al. / Work 9 (1977) 295-297
usually ignored' (Black, 1988). The personality of the expert therefore, plays an important part in the admissibility of evidence. However, the process of the Fry case (1923) which has been the test for admissibility of evidence for many years, has essentially been replaced with the results of the 1993 Supreme court ruling of Daubert vs. Merill-Dow Pharmaceuticals. The Daubert case has demanded that the scientific thought process be followed by expert witnesses before their testimony can be admitted as evidence in court. Take the directive of the judge in our example. He demanded of our witness that if the expert witness renders an opinion or description of a theory or technique, the expert must state: 1.
2. 3. 4.
5.
Whether that theory has been tested; has it been tested previously; and has the expert tested the theory in the specific case being litigated. Has the technique or theory been subject to peer review, and has it been published in some refereed journal. Is there a potential rate of error for the technique. At the time the technique was used, did standards exist for the technique, and were those standards followed in making the particular analysis that the expert conducted; and Is there general acceptance in the scientific community for the technique or analysis that is being presented by the expert witness?
This ruling clearly sets a tone of scientific theory to which expert witnesses must now adhere. No longer should we hear: 'In my 25 years of...' but rather, we should hear: 'The reliability and validity of the technique has been published and pertains to this case as follows .. .'. We may be a long way from that time in the field of ergonomics, but we should strive for that level of expertise. Let us examine the testimony that originally caught my eye. The following was taken from the transcript of an OSHA case that is currently on appeal. The expert witness, a certified professional ergonomist
who also has a doctorate in industrial engineering and teaches students of ergonomics, had identified the ergonomic stressor of long periods of standing during a job task analysis. While on the stand, the judge asked the witness to define the term 'long periods of standing' as the term pertained to the ergonomic stressor in question. The witness replied: Say if your were standing in one spot for 5 min and then moved to another location, then as you walk between a board, you had to stand in one position for an entire work-shift, or say if you started work at 8 and then got a break at 9.15 or 9.30 for 15 min, that is a long period to be in one specific spot'.
When questioned further about the definition of a long period of time, having been reminded of the need for adherence to the Daubert case philosophy, the expert concluded: 'If you stand in one position for 1 min, that is not a long period, but if you were to hold that posture and stand without moving for 5, 10, 15 min, that is a long period of standing without having moved'.
When asked to cite the reference supporting his response, he could not. However, he could recall: 'I've read articles that described long periods of standing, as I just described it'.
When questioned further: 'but you just can't recall the name of the articles; is that correct?' The witness responded: 'that is correct'. Thank goodness the judge did not ask the witness to explain the relation between the potential ergonomic stressor of long periods of standing and the development of the proposed pathology of varicose veins! As can be seen, these responses do not support the philosophy of Fry or Daubert. They defy scientific credibility, which reflect poorly on all ergonomists. There are no published reliable or valid studies addressing long periods of standing as an ergonomic stressor. As a matter of fact, there is a growing body of evidence matching ergonomic stressor identification with medical records that show just the opposite: no con-
D.L. Hart et al. / Work 9 (1997) 295-297
firmable relation between the performance of a job with ergonomic stressors and the development of a specific pathology. This may contradict our general theories and hypotheses, but we need facts to support our thoughts. The comments of the expert witness emphasize the need for each of us who function as expert witnesses to be prepared to defend our comments with literature or other evidence that follow scientific principles. We must state our answers concisely and precisely, and be prepared to compare our results to published data. When asked about ergonomic stressors, one should be prepared to discuss the definitions of our terms, the reliability and validity of our measurements used to identify the stressors, the relation between our measurements and the development of clinical symptoms, and the philosophies underlying our thought processes used to develop our opinions. If we are
297
not able to support our comments with literature, we should state precisely that. As the field of ergonomics evolves, we will discover many of the answers to the questions we are all asking, but until then, we must be honest about what we know and more importantly, what we do not know. In the mean time, the 'law should seek verdicts consistent with scientific reality, and with each other, and it can achieve this goal only be requiring scientific evidence to conform to the standards and criteria to which scientists themselves adhere'. References Black B. Evolving legal· standards for the admissibility of .scientific evidence. Science 1988;239:1508-1512. Fry vs. United States. 293 F. 1013 (DC Cir. 1923). Daubert vs. Merrell Dow Pharmaceuticals, Inc. 113 S. Ct. 2786 (1993).
ELSEVIER
Work 9 (1997) 295-297
Rehabilitation ergonomics
Witness: the truth please Dennis L. Hart a,*, Susan J. Isemhagen b , Leonard N. Matheson C a FOTO,
Knoxville, TN and Hart Ergonomic Consulting, Great Falls, VA, USA bIsemhagen Work Systems, Duluth, MN, USA C Washington University School of Medicine, Program in Occupational Therapy, St. Louis, MO, USA
While reviewing a deposition of an expert witness, it became evident that many of us follow different rules when we act as expert witnesses. But why the surprise? In the 'old days' (prior to 1993), we simply needed to have a 'heavy' curriculum vita and call ourselves an expert witness to be considered one on the stand; but what about the scientific principles of problem solving and the scientific principles of measurement? They should count, shouldn't they? Consider the Frye case (Fry vs. United States, 1923). This case is considered the case that 'articulated the now venerable rule of general acceptance' for forensic evidence. The pertinent part of the case focused on the thought process for accepting scientific evidence that emphasized the 'thing from which [a] deduction is made', rather than the way in which the deduction was made (Black, 1988). Over the years, courts have examined the bases from which evidence should be admitted; from facts or from deductive reasoning. Those decisions emphasizing the 'things' (i.e. following Fry) permitted thorough analyses of the facts, but the 'failure to focus on the question of reasoning and the standards of science can lead
*Corresponding author.
to less than adequate consideration of the scientific validity of expert opinions. Unfortunately, the alternative is the rejection of 'things' which according to Black (1988) may 'mean less judicial review of scientific evidence and more reliance of the adversary system to expose shortcomings to the jury'. Which ever approach a specific judge follows, 'decisions about the admissibility of scientific evidence will consistently accord with scientific reality only if courts look to the criteria and practice recognized by scientists. This holds true for medical as well as forensic science, but courts have been especially hesitant to examine the reasoning through which medical doctors reach their conclusions'. Simply supplant 'ergonomist' or 'therapist' for 'medical doctors' and you have the main point of this essay. The courts have deviated from scientific standards when accepting the opinions of physicians and ergonomists without demanding the scientific scrutiny of their thought process as well as the science of measurement concerning their facts. According to Black (1988) when the opinion of a medical expert is disputed, the courts typically look to the qualifications of the physician, 'the kind of facts upon which the opinion is based, and the certainty with which the opinion is expressed. The reasoning connecting facts to conclusions is
1051-9815/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved.
PII S1051-9815(97)00050-8
296
D.L. Hart et al. / Work 9 (1977) 295-297
usually ignored' (Black, 1988). The personality of the expert therefore, plays an important part in the admissibility of evidence. However, the process of the Fry case (1923) which has been the test for admissibility of evidence for many years, has essentially been replaced with the results of the 1993 Supreme court ruling of Daubert vs. Merill-Dow Pharmaceuticals. The Daubert case has demanded that the scientific thought process be followed by expert witnesses before their testimony can be admitted as evidence in court. Take the directive of the judge in our example. He demanded of our witness that if the expert witness renders an opinion or description of a theory or technique, the expert must state: 1.
2. 3. 4.
5.
Whether that theory has been tested; has it been tested previously; and has the expert tested the theory in the specific case being litigated. Has the technique or theory been subject to peer review, and has it been published in some refereed journal. Is there a potential rate of error for the technique. At the time the technique was used, did standards exist for the technique, and were those standards followed in making the particular analysis that the expert conducted; and Is there general acceptance in the scientific community for the technique or analysis that is being presented by the expert witness?
This ruling clearly sets a tone of scientific theory to which expert witnesses must now adhere. No longer should we hear: 'In my 25 years of...' but rather, we should hear: 'The reliability and validity of the technique has been published and pertains to this case as follows .. .'. We may be a long way from that time in the field of ergonomics, but we should strive for that level of expertise. Let us examine the testimony that originally caught my eye. The following was taken from the transcript of an OSHA case that is currently on appeal. The expert witness, a certified professional ergonomist
who also has a doctorate in industrial engineering and teaches students of ergonomics, had identified the ergonomic stressor of long periods of standing during a job task analysis. While on the stand, the judge asked the witness to define the term 'long periods of standing' as the term pertained to the ergonomic stressor in question. The witness replied: Say if your were standing in one spot for 5 min and then moved to another location, then as you walk between a board, you had to stand in one position for an entire work-shift, or say if you started work at 8 and then got a break at 9.15 or 9.30 for 15 min, that is a long period to be in one specific spot'.
When questioned further about the definition of a long period of time, having been reminded of the need for adherence to the Daubert case philosophy, the expert concluded: 'If you stand in one position for 1 min, that is not a long period, but if you were to hold that posture and stand without moving for 5, 10, 15 min, that is a long period of standing without having moved'.
When asked to cite the reference supporting his response, he could not. However, he could recall: 'I've read articles that described long periods of standing, as I just described it'.
When questioned further: 'but you just can't recall the name of the articles; is that correct?' The witness responded: 'that is correct'. Thank goodness the judge did not ask the witness to explain the relation between the potential ergonomic stressor of long periods of standing and the development of the proposed pathology of varicose veins! As can be seen, these responses do not support the philosophy of Fry or Daubert. They defy scientific credibility, which reflect poorly on all ergonomists. There are no published reliable or valid studies addressing long periods of standing as an ergonomic stressor. As a matter of fact, there is a growing body of evidence matching ergonomic stressor identification with medical records that show just the opposite: no con-
D.L. Hart et al. / Work 9 (1997) 295-297
firmable relation between the performance of a job with ergonomic stressors and the development of a specific pathology. This may contradict our general theories and hypotheses, but we need facts to support our thoughts. The comments of the expert witness emphasize the need for each of us who function as expert witnesses to be prepared to defend our comments with literature or other evidence that follow scientific principles. We must state our answers concisely and precisely, and be prepared to compare our results to published data. When asked about ergonomic stressors, one should be prepared to discuss the definitions of our terms, the reliability and validity of our measurements used to identify the stressors, the relation between our measurements and the development of clinical symptoms, and the philosophies underlying our thought processes used to develop our opinions. If we are
297
not able to support our comments with literature, we should state precisely that. As the field of ergonomics evolves, we will discover many of the answers to the questions we are all asking, but until then, we must be honest about what we know and more importantly, what we do not know. In the mean time, the 'law should seek verdicts consistent with scientific reality, and with each other, and it can achieve this goal only be requiring scientific evidence to conform to the standards and criteria to which scientists themselves adhere'. References Black B. Evolving legal· standards for the admissibility of .scientific evidence. Science 1988;239:1508-1512. Fry vs. United States. 293 F. 1013 (DC Cir. 1923). Daubert vs. Merrell Dow Pharmaceuticals, Inc. 113 S. Ct. 2786 (1993).
