Adverse impact
Adverse impact occurs when a hiring practice that appears neutral disproportionately excludes a protected group. It is assessed by outcome, not intent — a selection method can be entirely well-meant and still produce adverse impact.
A common screening heuristic in the US is the four-fifths rule: if the selection rate for one group is less than 80% of the rate for the highest-selected group, that is treated as an indicator warranting investigation. It is a rule of thumb, not a legal threshold.
Adverse impact analysis matters increasingly for AI-assisted hiring, where automated screening can apply a biased criterion consistently and at scale.