Three Misconceptions
There are three common misconceptions regarding causality in workers' compensation cases:
Causal determination is the same as the diagnosis of a suspected occupational disease
Just the presence of exposure or occurrence of an incident means that the related disease or injury has necessarily resulted from the workplace.
If all other potential causes of the disease have been ruled out, it must be a consequence of the employee's work.
Let's take the example of carpal tunnel syndrome (CTS):
Just the confirmation of the diagnosis of CTS in a worker does not make it necessarily a work-related disorder. It requires further assessment.
Even if the current occupation of the individual involves repetitive motions of the wrist (a common causal factor for CTS), the establishment of a causal relationship entails verification of sufficient intensity and duration of exposure preceding the diagnosis.
The ruling out non-occupational risk factors of CTS in the worker (such as diabetes or arthritis) does not mean we can infer it is work-related. Instead, a proper diagnosis requires demonstrating the presence of a putative causal agent in the workplace and sufficient exposure to the worker for the resulting effect.
Accordingly, a systematic approach to determine a cause-effect relationship in workers' compensation cases should address the following questions:
Regarding the diagnosis:
● Does the claimant have what is alleged?
● What were the specific diagnostic criteria used to make a diagnosis of the condition?
● Based on medical literature, what is the natural history of the illness, and what level of impairment can we predict?
● Has the injury or disease resulted in measurable functional loss?
Regarding injury or exposure:
● What are the known workplace and specific job exposures of the employee?
● Was there an actual injury or incident?
● Did the injury or incident occur before the disease?
● Has such a cause-and-effect relationship been demonstrated in the scientific literature?
● Was the injury of sufficient duration and extent to cause the illness?
● Are there other causes that are more likely to explain the effect?
Medical and Legal Causation
In workers' compensation cases, determination of causation means identifying the most probable cause of a worker's illness or disability and demonstrating that it resulted from work or the workplace. As the goal is to provide a just reparation to the worker for the physical and other damages from an injury, causality in workers' compensation involves both medical and legal aspects. These two may be mutually exclusive.
Medical causation deals with a scientific approach to cause and effect. For example, based on well-accepted scientific evidence, we may conclude that a particular exposure in a workplace is likely to cause a specific condition. As causation in science is considered multifactorial in origin, an illness or dysfunction is more likely to occur because of probable causes than by a single factor. To be considered a probable cause in medical research, a statistical association of 95% or more (P>.95) is generally required between an event and a given outcome.
Legal causation is dealt with in the courts from which our justice system developed. The court proceedings do not originate in science; the laws they uphold are historical and based on precedents. The essential purpose of finding the causal connection between a wrongful act and harm in law is to assign legal responsibility for the fair compensation of the victim.
Compared with medical causality, in the legal context, a relationship between an event and a given outcome is considered probable if the chance of their being related is greater than 50%.
Summary
In 1993, the US Supreme Court highlighted the difference between the aims of medical and legal causation as follows:
"There are important differences between the quest for truth in the courtroom and the quest for truth in the laboratory. Scientific conclusions are subject to perpetual revision. Law, on the other hand, must resolve disputes finally and quickly "... and that the Rules of Evidence were "designed not for the exhaustive search for cosmic understanding but for the particularized resolution of legal disputes." (Daubert v. Merrill Dow Pharmaceuticals, Inc. (1993)
This means that in workers' compensation cases, the eventual goal of determining a cause-and-effect relationship is to provide access to appropriate treatment, an opportunity to return to work, and compensation for any disability and financial losses to the injured worker without delay. We can accomplish such a goal by using the best available scientific evidence with the spirit of fairness and expeditious resolution of claims.
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