In order to answer questions posed by their clients, evaluating physicians must understand the context of a case or jurisdiction, in part because medical and legal perspectives may differ when an evaluator assesses issues such as causation and apportionment. A condition is not necessarily a ratable impairment, nor do symptomatic conditions necessarily prevent an individual from working. Attorneys may pose very specific apportionment questions based on laws unique to a given jurisdiction; for example, a patient may have an occupational injury or illness that results in impairment, but causation of the impairment may be multifactorial and may involve, for example, age-related degeneration, a pre-existing injury or illness, an occupational injury or illness, and/or subsequent trauma or disease. In some states, the presence of a pre-existing condition when an employee is injured may involve Second Injury Funds that were created to relieve a portion of the employer's/insurer's claim costs when the employer hired or retained an employee with a pre-existing medical condition who then suffered a “second” injury. The latter situation requires more extensive treatment and/or a greater disability due to the combined effects of both conditions. Apportionment of causation and impairment may be complex, requiring evaluation of nonoccupational and occupational risk factors and the natural history of the underlying condition.