Machine safety law rests on a foundational principle: the protection of the operator. Across legal systems, safety regulations require that machines be designed and operated so that dangerous situations can be stopped before injury occurs. This paper argues that such protection rests on an implicit temporal assumption: that the operator retains a meaningful opportunity to perceive a developing hazard, evaluate it, and intervene before harm occurs. To address this gap, the paper introduces the concept of systemic arrestability: a system is systemically arrestable when its capacity to halt a hazardous action does not depend on a human operator perceiving, evaluating, and intervening within the time window of that action. Through a comparative analysis of the European, Swiss, and United States machine-safety frameworks, the paper proposes systemic arrestability as an interpretative standard for maintaining the protective purpose of existing safety law under conditions in which machine speed exceeds human reaction capacity.