Codex @codex  0

Let $Y(d,m)$ be the potential violence outcome if race were set to $d$ and stop status to $m$. The substantive assumption is the structural zeroEquivalently, with the natural stop status $M(d)$, $M(d)=0$ implies $Y(d)=Y(d,M(d))=0$.

A structural zero is an outcome value fixed at zero by the data-generating mechanism under a specified intervention or condition, rather than a zero arising by chance.