## Facts

- An employee carpenter suffered a compensable industrial eye injury when a nail penetrated his eye.
- The eye injury caused ongoing visual impairment, including double vision and depth-perception difficulty.
- While recuperating at home, the employee used a power saw to cut lumber for a personal project and accidentally amputated a finger.
- The employee claimed the impaired vision from the industrial eye injury caused him to misjudge the saw and led to the amputation.
- The insurer argued the home activity and the employee’s alleged negligence were an independent intervening cause breaking causation.
- The Industrial Accident Commission found the finger amputation was causally related to the eye injury and awarded benefits; it rejected the intervening-negligence argument.

## Issues

1. Whether a later injury incurred during a nonindustrial home activity is compensable as a consequential injury flowing from a prior industrial injury when supported by evidence of causal linkage.
2. Whether the employee’s conduct in operating the saw constituted intervening negligence that, as a matter of law, severed the causal chain and barred compensation.
3. What level of deference a reviewing court owes to the Commission’s causation findings under the substantial-evidence standard.

## Decision

- The Court of Appeal denied the insurer’s request to annul the award and affirmed the Commission.
- The court held substantial evidence supported the finding that the visual impairment from the compensable eye injury caused the later finger amputation.
- The court held the insurer did not establish an independent intervening cause as a matter of law; any negligence and its effect on causation were factual matters for the Commission.

## Legal Principles

- Workers’ compensation liability includes subsequent injuries that are the direct and natural result of an initial compensable industrial injury, even if the later injury occurs away from work during ordinary nonindustrial activity.
- Proximate cause and factual causation in workers’ compensation cases are primarily for the Commission; reviewing courts do not reweigh evidence and will uphold findings supported by substantial evidence.
- An employee’s ordinary negligence in later conduct does not automatically break the causal chain; only a truly independent, unforeseeable, or grossly unreasonable intervening act may sever causation as a matter of law.

## Conclusion

The court sustained an award for a finger amputation suffered at home because the Commission could reasonably find it was caused by impaired vision from an earlier industrial eye injury, and the insurer failed to show an intervening negligent act that legally cut off compensation.


State Comp. Ins. Fund v. Indus. Accident Comm'n, 176 Cal. App. 2d 10 (Cal. Ct. App. 1959)