What the four-fifths rule actually tells you
It is a quick screen for adverse impact. Compare how often each group is selected. If one group is chosen at less than 80% of the rate of the top group, the process gets flagged for a closer look. The flag is a starting point, not a verdict, and the number breaks down on small teams. Here is how to run it and how to read the result.
How this note is governed
Applies to US employers running any decision that selects some people over others. The Uniform Guidelines at 29 CFR 1607.4(D). Federal enforcement has been deprioritized since 2025; private and state claims remain available.
Short answer
Below 80%. Divide each group's selection rate by the highest group's rate. Since 1978 the Uniform Guidelines have treated a result below four-fifths, or 80%, as a sign of adverse impact. It is a screening flag, not a finding.
Published Last verified
Added Executive Order 14281 and the 9 June 2026 Justice Department opinion deprioritizing federal disparate-impact enforcement. The 80% line in 29 CFR 1607.4(D) is unchanged.
- Since 1978
- Four federal agencies adopted the Uniform Guidelines that define the rule. They are still in the Code of Federal Regulations today.
- Below 80%
- An impact ratio under four-fifths is the line the federal guidelines treat as evidence of adverse impact. At or above it generally is not.
Compare selection rates, group against group
The four-fifths rule does not look at how many people from each group were hired. It looks at the rate at which each group was selected from the pool that was actually considered. A group can be a small share of your applicants and still clear the rule. It can be a large share and still trip it. The test is about the odds of being selected, not the headcount. The math is four short steps.
- Find each selection rate. For every group, divide the number selected by the number considered. If 48 of 80 applicants are hired, that group’s selection rate is 60%.
- Find the top rate. Identify the group with the highest selection rate this round. Every other group is measured against it, so the reference is whichever group came out on top, not a fixed group.
- Take the impact ratio. Divide each group’s rate by that top rate. A group selected at 42% against a top rate of 60% has a ratio of 0.70.
- Read the result. Any ratio below 0.80, or 80%, is treated as evidence of adverse impact and a signal to dig into that step of the process. A ratio at or above 0.80 generally is not.
Its Adverse-Impact Review runs the four-fifths check across age, sex, and race or ethnicity on your selection list before a reduction. You see a flagged group while you can still revisit the decision.
Running the numbers on one hiring round
Say you posted a role, two groups applied, and you want to check the screen before you make offers. You count only the people who actually applied for this role, not your whole workforce, and you run the rates.
- Top rate 60%
- The group with the highest selection rate had 80 applicants and 48 offers. 48 divided by 80 is 0.60, so the rate is 60%. This becomes the benchmark every other group is measured against.
- Compared group 42%
- A second group had 50 applicants and 21 offers. 21 divided by 50 is 0.42, so the rate is 42%. On raw counts this looks unremarkable, which is exactly why the ratio matters.
- Impact ratio 0.70, a flag
- 42% divided by 60% is 0.70, or 70%. That sits below the four-fifths line, so this round is flagged for adverse impact. The flag does not say you discriminated. It says look at why the rates diverged and whether the screen is doing real work.
If the second group’s rate had landed at 48% instead, the ratio would have been 0.80 exactly, and the round would clear the rule. That small gap, six offers either way in this example, shows how close these calls can be and why the next two sections matter.
A screening flag, not a finding of discrimination
A flag means the process deserves a closer look, nothing more. The guidelines themselves are careful about this in both directions. A gap smaller than four-fifths can still count as adverse impact when it is significant in statistical and practical terms. A gap larger than four-fifths may not count when it rests on small numbers that are not statistically significant. So the bare ratio is a first read, not the last word.
When a process is flagged, a legal question follows under Title VII. The first half is whether the practice that caused the gap is job related and consistent with business necessity. The second is whether a less discriminatory alternative was available and skipped. A flag opens that inquiry. It does not settle it.
A pass is not a clean bill of health, and a flag is not proof. Clearing the rule does not show that a selection step is fair or job related. It can pass and still screen out a group for no good reason on a small sample. And failing it does not prove discrimination. It points you to the practice that produced the gap so you can test whether that practice is defensible. Treat the number as a flashlight, not a verdict.
Any decision that selects some people over others
Hiring is the textbook case, but the four-fifths rule travels. The same logic applies to who gets promoted and who is chosen for a development program. It also applies to who is kept or let go when a team is reduced. Anywhere you select a subset from a larger group, the selection rate exists and the check can run.
It also reaches the tools that make those decisions for you. Resume screeners, assessment cut scores, and AI hiring software all produce selection rates. Adverse impact is one of the first things they get tested against. An automated step that quietly screens one group at a lower rate carries the same exposure as a human one, and often more. It runs at scale and leaves a record.
The rule gets unstable on small groups
The four-fifths rule was built for large applicant pools, and it wobbles badly on small ones. With a handful of candidates, one or two decisions swing the ratio across the line in either direction. That is the precise reason the guidelines say a gap based on small numbers, not statistically significant, may not be adverse impact at all. On a small team, run a significance test before you act on a bare ratio. Bring in help if a real decision rides on it. Three things trip up the calculation most often.
- Small pools swing the ratio.One extra hire can move a group above or below 80%. A flag from a tiny sample is noise until a significance test says otherwise. The guidelines suggest running the analysis for any group that is at least 2% of the relevant workforce.
- The reference group can shift.The benchmark is whichever group has the highest selection rate in this round, not a fixed group you decide ahead of time. It can change from one hiring cycle to the next, so recompute it each time rather than assuming.
- The wrong population gets counted.Use only the people actually considered for the decision: applicants for a hire, candidates for a promotion, the pool in scope for a reduction. Folding in people who never entered the process distorts every rate and the ratio with it.
Federal enforcement has pulled back, the law has not
The rule lives inside a federal regulation, the Uniform Guidelines on Employee Selection Procedures. The EEOC and three other agencies adopted it in 1978, and it still appears in the Code of Federal Regulations. The thing that changed recently is enforcement posture, not the rule.
In April 2025, an executive order directed federal agencies to deprioritize disparate-impact enforcement and to review or unwind matters built on the theory. That is a real shift in how the federal government pursues these cases. It does not erase the underlying exposure, because an executive order cannot rewrite a statute or overrule the Supreme Court. Disparate impact is written into Title VII by the Civil Rights Act of 1991. The Supreme Court recognized it in 1971 in Griggs v. Duke Power. Private plaintiffs can still bring disparate-impact claims, and several state laws, including those in California, New York, and Illinois, keep the theory firmly in force.
The pullback deepened in June 2026. On 9 June 2026 the Justice Department’s Office of Legal Counsel issued an opinion at the EEOC chair’s request. It concludes that the EEOC’s longstanding disparate-impact guidelines are unconstitutional as applied. In the opinion’s view, impact evidence should function mainly as evidence of intentional discrimination, rather than a freestanding basis for liability. An employer’s defense would then need only show a reasonable business purpose, rather than strict business necessity. An OLC opinion binds the executive branch’s enforcement posture. It does not amend Title VII, overrule Griggs or the 1991 Act, or bind federal courts, private plaintiffs, or state agencies. The practical read is unchanged. The check still takes minutes, and private and state exposure still exists. A flagged practice you cannot connect to the job is still a risk worth fixing.
So the federal scrutiny has eased while the risk in court and under state law has not. For an employer the practical move is unchanged. Run the check. When a process is flagged, confirm the practice that caused it is job related before you rely on it. This is also an area in motion, so the guidelines themselves could be revised. The date on this note is when these facts were last confirmed.
Before you change a selection process, defend a flagged one, or act on an adverse-impact finding, get legal advice. The analysis turns on facts a calculator cannot see. The stakes are highest in a layoff or a termination, where a flagged selection can become the center of a claim. This is general information.
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Where these figures come from
5 citations checked, newest check 21 July 2026
- Uniform Guidelines on Employee Selection Procedures, 29 CFR 1607.4(D). The federal regulation that defines the four-fifths rule. A selection rate below four-fifths, or 80%, of the highest group’s rate is generally regarded as evidence of adverse impact. Smaller gaps can still count if statistically and practically significant. Larger gaps may not count if based on small numbers. Adopted jointly in 1978 by the EEOC, the Civil Service Commission, the Department of Labor, and the Department of Justice. ecfr.gov, 29 CFR 1607.4 ecfr.gov
- Title VII disparate impact, 42 U.S.C. 2000e-2(k). The statute, added by the Civil Rights Act of 1991, that makes disparate impact unlawful and sets the burden-shifting test. The claimant shows a practice causes a disparate impact. The employer must show it is job related and consistent with business necessity. The claimant may still prevail by showing a less discriminatory alternative existed. Rooted in Griggs v. Duke Power Co., 401 U.S. 424 (1971). law.cornell.edu, 42 U.S.C. 2000e-2 law.cornell.edu
- EEOC, Employment Tests and Selection Procedures. The agency’s guidance explains that determining whether a selection procedure has a disparate impact ordinarily requires a statistical analysis. A flagged procedure must then be shown to be job related and consistent with business necessity. eeoc.gov, employment tests and selection procedures eeoc.gov
- Executive Order 14281, Restoring Equality of Opportunity and Meritocracy. Signed 23 April 2025 (90 FR 17537), directing federal agencies to deprioritize disparate-impact enforcement and to review matters built on the theory. The order does not amend Title VII or overrule Supreme Court precedent, so private and state disparate-impact claims remain available. federalregister.gov, EO 14281 federalregister.gov
- Department of Justice, Office of Legal Counsel opinion on the EEOC’s disparate-impact guidelines, 9 June 2026. Concludes, for the executive branch, that the EEOC’s disparate-impact guidelines are unconstitutional as applied. It treats impact evidence primarily as evidence of intent. It softens the employer’s defense from business necessity to a reasonable business purpose. Not a court ruling: it does not amend Title VII, overrule Griggs, or bind courts, private plaintiffs, or state enforcement. justice.gov, OLC opinions justice.gov
Common questions
What is the four-fifths rule in plain terms?
A quick check for unequal selection. You compare how often each group is chosen. If one group is selected at less than 80% of the rate of the group chosen most often, the process gets flagged. That flag is a cue for a closer look. It comes from a 1978 federal regulation and is sometimes called the 80% rule.
Does failing the four-fifths rule mean I broke the law?
No. A flag is the start of the analysis, not the conclusion. It points to a practice that produced a gap. The next question is whether that practice is job related and consistent with business necessity, and whether a less discriminatory alternative was skipped. A flagged process can be perfectly lawful once that is shown, and an unflagged one is not automatically safe.
Is the four-fifths rule still in effect after the 2025 executive order?
The April 2025 executive order told federal agencies to deprioritize disparate-impact enforcement, but it did not change the law. Disparate impact is written into Title VII by the Civil Rights Act of 1991 and recognized by the Supreme Court in Griggs. A June 2026 Justice Department opinion goes further for federal enforcers, treating impact mainly as evidence of intent, but it binds only the executive branch. Private lawsuits and several state laws keep the theory in force. So the safe practice has not changed. Run the check, and confirm a flagged practice is job related.
Does the rule work for a small team?
Use it with care. The ratio is unstable when only a few people are involved, because one decision can swing it past the line. The guidelines themselves say a gap based on small numbers, not statistically significant, may not be adverse impact. So on a small pool, run a significance test rather than acting on the bare ratio. Get help if a real decision depends on it.
Does it apply to layoffs and promotions, or only hiring?
Any selection decision. Hiring is the common example. But promotions, training selections, and who is kept in a reduction all produce selection rates you can compare the same way. It also applies to automated screeners and AI hiring tools, which is why those get tested for adverse impact.
Put it to work
Run this exact check in the browser. Enter each group considered and selected, and see every rate, every ratio, and any group below the 80% line.
FreeIts Adverse-Impact Review runs the four-fifths check across age, sex, and race or ethnicity on your selection list before a reduction. You see a flagged group while you can still revisit the decision.
$129For the screening tools and AI hiring software where adverse impact gets tested and governed. Both walk through scoring a tool for risk, documenting it, and keeping a person in the loop.
$89To see how your promotion and internal pay decisions land across groups, the other place selection patterns surface.
$29
This note is general information about employment practice rather than legal advice for your situation. Check the review date and the jurisdictions above, follow the source link, and confirm the rule before you act on it.