Workers’ Compensation · Primary-source case analysis

Benson: Successive Injuries Generally Require Separate Disability Awards

By Aneeta Mishra and Timothy Chan

Published April 24, 2026

Benson explains how Senate Bill 899’s causation rules changed permanent-disability awards when multiple industrial injuries contribute to an employee’s overall disability.

Two injuries produced one combined award

Dianne Benson sustained a specific neck injury and a cumulative-trauma injury that became permanent and stationary at the same time. The workers’ compensation judge combined the disability from both injuries into one award under Wilkinson.

Causation-based apportionment displaced the general Wilkinson rule

Labor Code sections 4663 and 4664 require disability to be apportioned by cause and limit each employer’s liability to the disability directly caused by the injury. The Board concluded that those provisions generally require the contribution of each industrial injury to be identified separately.

A narrow exception remains

The Board recognized that a combined award may still be justified when physicians cannot, within reasonable medical probability, parcel out the approximate causal contribution of successive injuries. That exception requires a developed medical record rather than an assumption that the disabilities should be combined.

Disposition

The WCAB rescinded the combined award and returned the matters for separate permanent-disability awards. The decision focused on allocation between injuries, not whether the worker had sustained compensable disability.

Key takeaways

• Identify every industrial and nonindustrial cause of permanent disability.
• Ask the physician to allocate causation injury by injury.
• Use separate awards unless substantial medical evidence supports the narrow exception.
• Do not confuse overlapping body parts with inseparable causation.