--- title: "What is the Four-Fifths Rule? Definition | SocialTalent" description: "The four-fifths rule is the US EEOC threshold for flagging potential adverse impact in hiring — a screening tool, not a final verdict." url: "https://www.socialtalent.com/glossary/four-fifths-rule" last_modified: "2026-04-27T15:49:32+00:00" --- [Home](https://www.socialtalent.com/) » [Glossary](https://www.socialtalent.com/glossary/) » Four-Fifths Rule # What is the Four-Fifths Rule? The four-fifths rule (also called the 80% rule) is a US legal guideline used by the EEOC and federal courts to identify potential adverse impact in hiring. It flags when the selection rate for any protected group falls below 80% of the rate for the highest-selected group. #### By Lee Flanagan 27th Apr. 2026 | Last Updated: 27th Apr. 2026 ## Extended definition The four-fifths rule comes from the Uniform Guidelines on Employee Selection Procedures, jointly issued by the EEOC, Department of Justice, Department of Labor, and Civil Service Commission in 1978. It’s a US-specific framework that other jurisdictions don’t apply directly, though some have analogous concepts. The rule provides a rough numeric trigger for further investigation rather than an absolute prohibition — selection rates that fall below the 80% threshold are flagged as potentially showing adverse impact, which then becomes a question of whether the selection process can be justified as job-related and consistent with business necessity. It’s one of the most-cited frameworks in US adverse-impact analysis but is also widely understood as a screening tool, not the final word on whether a process is discriminatory. ## How the four-fifths rule works The calculation: `Selection rate = (Number of candidates from group hired ÷ Number of candidates from group who applied)` Then for any protected group: `Comparison ratio = Selection rate for protected group ÷ Selection rate for highest-selected group` If the ratio falls below 0.80 (80%), the selection process is flagged as potentially showing [adverse impact](https://www.socialtalent.com/glossary/adverse-impact). A worked example: if 60% of male applicants get hired and 40% of female applicants get hired, the comparison ratio is 0.40/0.60 = 0.67, which falls below 0.80. The process would be flagged for further analysis under the four-fifths rule. The framework applies to “protected classes” under US federal law — race, colour, religion, sex, national origin, age (40+), disability, and others. Comparisons are typically done between the highest-selected group and each other identifiable group. A flagged result doesn’t automatically mean the process is discriminatory. The next step is usually validation — whether the selection process can be shown to be job-related and consistent with business necessity. Selection processes that survive validation may continue even if they produce disparate outcomes; processes that don’t survive validation typically need redesign. The rule has limitations. Small sample sizes can produce statistically meaningless ratios. Some statisticians prefer significance-testing approaches. Recent legal scholarship has questioned the four-fifths threshold in various ways. But it remains the most widely-cited rough screen in US adverse-impact practice. ## Why the four-fifths rule matters The four-fifths rule is the most commonly used quantitative test for adverse impact in US hiring. For TA functions operating in the US, it’s a baseline analytical step in monitoring whether selection processes are producing disparate outcomes. Failing the four-fifths threshold doesn’t automatically produce legal liability, but it does typically trigger investigation, justification requirements, and sometimes process redesign. For multi-jurisdictional employers, the rule applies to US operations but not to UK, EU, or other jurisdictions which have their own analytical frameworks. ## Common mistakes and misconceptions about the four-fifths rule - **Treating it as global** — The four-fifths rule is US-specific. UK, EU, Asian, and other jurisdictions have their own adverse-impact frameworks that don’t use the 80% threshold. International employers need jurisdiction-specific analysis. - **Treating it as a final verdict** — The rule flags potential adverse impact for further investigation. A failed test doesn’t automatically mean discrimination; a passed test doesn’t automatically mean fairness. It’s a screening tool. - **Applying it to small samples** — Sample sizes under 30 produce ratios that may be statistically meaningless. Some adverse-impact analyses use the four-fifths rule alongside statistical significance tests for small samples. - **Confusing the rule with quotas** — The four-fifths rule is an analytical screen for disparate selection outcomes, not a hiring requirement. It doesn’t mandate quotas or specific demographic outcomes; it identifies processes that may need investigation. - **Applying it only to hiring** — The framework also applies to promotions, terminations, and other selection decisions. Many employers focus only on hiring and miss adverse-impact patterns elsewhere in the employee lifecycle. Related training ### Interviewing Training — License to Hire Give hiring managers the skills to run interviews that actually predict job performance. [Explore interviewing training →](https://www.socialtalent.com/interviewing-training) From the course library ## Recommended learning paths - 4 missions ### [How To Build An Inclusive Hiring Process](https://www.socialtalent.com/course-library/learning-path/how-to-build-an-inclusive-hiring-process) Adjust practices when one group fares worse in your process, the problem a four-fifths check flags. By **Joanna Abeyie, Joanne Lockwood, Roy Baladi & Yasmin Sheikh** - 1 mission ### [How To Lead DEI Conversations As A Talent Advisor](https://www.socialtalent.com/course-library/learning-path/how-to-lead-dei-conversations-as-a-talent-advisor) Define anti-bias hiring criteria and widen equal access when selection rates start to diverge. By **John Vlastelica** [Browse the full course library →](https://www.socialtalent.com/course-library) ## Frequently asked questions What is the four-fifths rule? The four-fifths rule (also called the 80% rule) is a US legal guideline used by the EEOC and federal courts to identify potential adverse impact in hiring. It flags when the selection rate for any protected group falls below 80% of the rate for the highest-selected group. It's a US-specific framework that other jurisdictions don't apply directly, though some have analogous concepts. Does the four-fifths rule apply outside the US? No. The four-fifths rule is specific to US federal frameworks (the Uniform Guidelines on Employee Selection Procedures). Other jurisdictions have their own adverse-impact analytical frameworks — the UK, EU, Canada, Australia, and others use different tests. International employers need jurisdiction-specific analysis rather than applying the US rule globally. What happens if a selection process fails the four-fifths rule? The process is flagged for further analysis. Failing the threshold doesn't automatically mean the process is discriminatory; the next step is validation — whether the process can be shown to be job-related and consistent with business necessity. Validated processes may continue even if they produce disparate outcomes; non-validated processes typically need redesign. How do you calculate the four-fifths rule? Calculate selection rate for each demographic group (hired / applied). Divide each group's selection rate by the rate for the highest-selected group. If any ratio falls below 0.80, the process is flagged. Example: 40% female selection rate divided by 60% male selection rate = 0.67, which falls below the 80% threshold. Is the four-fifths rule the same as a hiring quota? No. The four-fifths rule is an analytical screen for disparate outcomes, not a hiring requirement. It identifies selection processes that may produce adverse impact and may need investigation. It doesn't mandate specific hiring outcomes or impose quotas. Quotas are a separate (and more legally restricted) mechanism in US law.