In another installment on a continuing series of apportionment, CA DWC Regional Manager Mark Kahn now examines the application of CA Labor Code section 4750.

L.C. 4750 provides that an employee who suffers from a previous permanent disability or physical impairment and who sustains a subsequent injury shall not receive from the employer compensation for his pre-existing permanent disability or impairment. The employer is liable only for that portion of disability caused by industrial injury.

Under L.C. 4750 the apportionment must be to an actual disability pre-existing the industrial injury. Again apportionment to causes or to pathology is not legal apportionment (Gay v. WCAB, supra).

Since the employer has the burden of proof, he must show that prior to the compensable injury, the employee already had a disability when attempting to compete in the open labor market, or an impairment of earning capacity, or an impairment of the use of a member. This can be shown by evidence of a prior finding or award or by other evidence that disability actually existed prior to the industrial injury.

In Gay the court wrote as follows: In order for the Board to rely upon a physician's evaluation as to apportionment under section 4750, the physician must disclose adequate familiarity with the preexisting disability. That is, the physician must describe in detail the exact nature of the preexisting disability and the basis for such an opinion in order for the Board to be able to determine that the physician properly apportioned under correct legal principles.

When considering apportionment under L.C. 4663, whether the employee was asymptomatic is irrelevant. On the other hand, L.C. 4750 requires that the employee have an actual disability pre-existing the industrial injury. Here the issue of whether or not the employee was symptomatic is very important. If the employee was symptomatic prior to the industrial injury, it may show that he had disability pre-existing. If the employee was not experiencing prior symptomatology, that could demonstrate that he had no disability pre-existing the industrial injury. Remember that the disability to be proved is one that would have been a ratable disability had it been an industrial injury. For example, if the employee had intermittent minimal pain as a result of a non-industrial automobile accident before the compensable injury, there would be no apportionment because intermittent minimal pain is not a ratable disability in a workers' compensation setting. But if the employer can show that the reason the employee was previously asymptomatic is that he worked in a congenial environment, then apportionment under L.C. 4750 may be proper. Another example would be an employee with a prior workers' compensation award for an old injury which resulted in a work restriction of no heavy work. If he was asymptomatic prior to the industrial injury, that may be evidence that there is no prior disability. However, if the employer can show that the employee continued to observe his work restrictions, and that the reason he was asymptomatic was that he continued to work in an environment congenial with his restrictions, apportionment could be proper (Callahan v. WCAB, 43 CCC 1907).

To apportion under L.C. 4750, there must be an event or condition that led to disability which pre-existed the industrial injury. That condition or event could be a prior industrial injury, a non-industrial accident, a disease, or a situation in which the employee merely developed pain, atrophy, limitation of range of motion, or loss of visual or hearing acuity. It is possible that the employee suffered from a congenital defect which caused isability.

Once the determination is made that there was some event or condition that existed prior to the industrial injury, the defendant must then show that this event or condition was actually disabling immediately prior to the compensable injury.

Pre-existing disability can be established by proving that the employee was receiving medical treatment for the condition or event prior to the industrial injury. Medical records showing that the employee had consulted a doctor and complained of pain is evidence of pre-existing disability. Evidence that the employee missed time from work prior to the industrial injury due to pain or discomfort in the same part of the body alleged as the industrial injury, demonstrates pre-existing disability. Testimony from the employer that the employee complained of pain following a day's work is evidence of pre-existing disability.

Pre-existing disability cannot be established by imposing a retroactive, prophylactic work restriction due to a pre-existing condition after a subsequent industrial injury occurs, unless the worker was actually restricted in his work activity prior to the industrial injury (Franklinv. WCAB, supra; Amico v. WCAB, 39 CCC 845). However, where the injured worker was actually under a prophylactic restriction for a pre-existing condition or event at the time the subsequent industrial injury occurs, apportionment to pre-existing disability is proper. It is only the retroactive application of a prophylactic restriction to an otherwise non-existent previous disability that is prohibited (Bookout v. WCAB, 41 CCC 595).

There can be objective evidence of a pre-existing disability, such as an amputation, or that the employee restricted his activities. For example, this evidence might be in the form of testimony from the employer that the employee stated he had back problems and would not do certain types of lifting or lift certain weight. This could be valid evidence of a preexisting disability.

The question to be determined by the trier of fact is, prior to the industrial injury, was the employee suffering from a disability of such a nature that a workers' compensation permanent disability award would have been given for that disability? As can be seen, the definition of a pre-existing, permanent disability is the same as that for permanent disability for rating purposes. The disability that pre-existed the injury must be a disability which causes an impairment of earning capacity, impairment of normal use of a member, or a competitive handicap on the open labor market (Luchini v. WCAB, 35 CCC 397).

Mark Kahn is a Regional Manager for the Department of Workers' Compensation, Division of Industrial Relations, State of CA.