Disparate impact is the discrimination theory that keeps HR analytics teams busy. Unlike disparate treatment, which turns on intent, disparate impact is about numbers. A hiring test produces different pass rates by race; a promotion policy elevates fewer women than men; an educational credential requirement excludes disproportionately from certain demographic groups. None of these require a discriminatory motive to create legal exposure, which is why proactive analysis is the primary defense. The companies that run adverse-impact analysis as part of their standard HR practice catch problems before they become charges; the ones that don't find out from the EEOC.
The Griggs Framework and the 1991 Civil Rights Act The Supreme Court's 1971 decision in Griggs v. Duke Power Co. established that Title VII prohibits not just intentional discrimination but also neutral practices that produce disparate impact without business necessity. The 1991 Civil Rights Act codified the framework and clarified the burden-shifting. Step one: the plaintiff shows that a specific practice caused disparate impact. Step two: the employer must prove the practice is job-related for the position and consistent with business necessity. Step three: even if the employer meets step two, the plaintiff can win by showing an alternative practice with less disparate impact exists and the employer refused to adopt it.
The framework applies to hiring, firing, promotion, testing, credentialing, scheduling, and nearly any practice that filters employees or applicants.
The 80% Rule in Practice The EEOC's 80% rule (technically the four-fifths rule) is a rough screen, not a legal standard. If the selection rate for any protected group is less than 80% of the rate for the group with the highest selection rate, the EEOC considers that evidence of adverse impact. Example: if 50% of male applicants get hired but only 35% of female applicants get hired, the ratio is 35/50 = 70%, below the 80% threshold. That flags the hiring process for further review.
Does Passing the 80% Rule Mean the Policy Is Legal? No. The 80% rule is a screening threshold; statistical significance tests and smaller-sample adjustments apply in court. A policy that technically passes the 80% screen can still be challenged, and a policy that fails can still be defended with strong business-necessity evidence. The screen is a starting point for analysis, not a green light or a red flag by itself.
Where Disparate Impact Shows Up Most Often Five categories generate most disparate-impact cases. Pre-employment tests (cognitive, personality, physical) with validated different performance across groups. Educational or credential requirements that exclude disproportionately. Criminal-history screens. Credit-history screens. And AI-driven hiring tools where the underlying training data encoded historical bias. The last category has become a major area of 2025-2026 enforcement, with the EEOC publishing specific guidance on algorithmic discrimination and several state AGs bringing cases against automated hiring tools.
Running Disparate-Impact Analysis and Documenting the Work Annual adverse-impact analysis across hiring, promotion, termination, and compensation is the baseline. Break outcomes down by race, sex, age, and disability status where data allows. Flag any category under the 80% rule for deeper analysis. Validate any pre-employment test against actual job performance, not just generic aptitude. Document everything, because the analysis itself becomes evidence either that you took reasonable steps or that you didn't. Platforms like AllVoices' HR case management tool help employee relations and compliance functions centralize the data that makes pattern detection possible. The companies that integrate disparate-impact analysis into standard reporting cycles stay ahead of the risk; the companies that treat it as an occasional audit activity don't.
The EEOC publishes the Uniform Guidelines on Employee Selection Procedures at eeoc.gov . OFCCP publishes adverse-impact analysis guidance for federal contractors at dol.gov/agencies/ofccp .
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