Quick Answer: Personality tests are legal in hiring under US law, but they are regulated. The EEOC treats any standardized test as an "employment selection procedure." If a test produces adverse impact—meaning protected groups score systematically lower—the employer must prove the test is job-related and consistent with business necessity. Many personality tests have not been validated as job-predictive, which means they are legal to use but legally risky if they correlate with protected characteristics. Unvalidated tests are lower-risk when used for team-building or coaching, higher-risk when used as screening gates.
The Legal Framework: EEOC Guidelines and Adverse Impact
In the United States, personality tests in hiring are regulated under Title VII of the Civil Rights Act via the EEOC's Uniform Guidelines on Employee Selection Procedures (adopted 1978, reaffirmed in recent guidance). Here is what you need to know if you work in hiring or apply for jobs that include personality assessment.
The four-fifths rule. If a test produces hiring rates that differ significantly by protected group (race, gender, age, disability, etc.), the test has adverse impact. The EEOC uses the "four-fifths rule" as a rough threshold: if the hiring rate for the protected group is less than 80% of the hiring rate for the favored group, there is presumptive adverse impact. Example: if 50% of men pass a test but only 30% of women pass it, and women are hired at a lower rate as a result, the test has adverse impact.
Burden of proof shifts to the employer. Once adverse impact is shown, the burden of proof shifts to the employer. They must prove the test is "job-related" and "consistent with business necessity." Job-related means the test predicts actual job performance. Business necessity means the employer has a significant operational need that the test addresses. An unvalidated personality test is hard to defend because there is no evidence it predicts performance in the role.
Validation is the legal shield. If an employer can demonstrate through a validation study that a test predicts job performance in a specific role, the test can continue even if it has adverse impact. However, most personality tests used in hiring are not formally validated for job prediction. They are used because HR feels they are useful or they are part of a vendor's toolkit. A test without validation backing is legally vulnerable.
Which Tests Are Legally Safer (And Which Are Not)
MBTI (Myers-Briggs Type Indicator). MBTI is widely used in hiring and team-building, but it is not legally validated as a job-performance predictor. The test itself is not illegal; it is just not backed by research showing it predicts who will be a good engineer, manager, or salesperson. MBTI is legally safer when used for team-building, communication coaching, or self-awareness—contexts where no one is rejected based on their type. It is legally riskier if a hiring manager says "We only hire ENTJs" or uses type scores as a screening gate. Several meta-analyses find little to no correlation between MBTI type and job performance, which weakens the employer's "job-related" defense if challenged.
DiSC (Dominance, Influence, Steadiness, Conscientiousness). Similar to MBTI, DiSC is used for communication and leadership coaching and is generally considered lower-risk in hiring contexts. However, DiSC also lacks substantial peer-reviewed evidence as a job-performance predictor. It is safer in advisory roles (coaching, team communication) than in pass-fail screening.
Big Five Personality Inventory. The Big Five (Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism) is the most legally defensible personality test for hiring because it has peer-reviewed evidence of job-relatedness in some domains. Roberts et al. (2007) meta-analysis found that Conscientiousness correlates modestly with job performance across most roles (r = 0.31), and other dimensions correlate with specific roles. An employer using a validated Big Five assessment can argue job-relatedness, though they still must monitor for adverse impact.
Unvalidated or proprietary tests. Many companies use proprietary personality tests or off-the-shelf assessments without peer-reviewed validation. These are legally dangerous for hiring decisions because the employer cannot easily prove job-relatedness if challenged. They are safer for advisory, non-gating use.
What the Data Says About Personality Tests and Job Performance
MBTI and job performance. A 2019 meta-analysis by Capraro et al. found that MBTI has "essentially zero" correlation with job performance when measured objectively (r < 0.10). MBTI predicts self-reported satisfaction and communication style, but not productivity, error rates, or promotion outcomes. Using MBTI as a hiring gate is legally vulnerable because the employer cannot prove it predicts the job-relevant outcomes.
Big Five and job performance. Conscientiousness correlates with job performance at r = 0.31 (moderate), and the correlation is consistent across most roles (Roberts et al., 2007). Openness correlates with training performance and creativity. Extraversion correlates modestly with leadership and sales roles (r = 0.16). An employer can cite these findings to defend a validated Big Five assessment. However, the correlations are modest, and they do not hold equally across all job types, which still leaves room for legal challenge.
Adverse impact on protected groups. Some personality assessments, if scored against unstandardized norms or cut-off scores, can produce disparate impact. For instance, if a personality test designed on a US college-student sample is used to screen immigrants or older workers, those groups might score systematically lower—not because they are worse fits, but because the test norms do not account for cultural or generational differences. EEOC settlements with technology companies (iTutorGroup, Workday) have involved hiring tools that screened against protected groups, including age discrimination through algorithmic scoring (Mobley v. Workday, 2025).
Common Legal Mistakes With Personality Tests in Hiring
- Using an unvalidated test as a gating criterion. A company uses a proprietary personality test and rejects all candidates below a cut-off score without evidence the test predicts job performance. If the test produces adverse impact, the employer has no validation study to defend the practice. Risk: EEOC complaint and potential settlement.
- Failing to monitor for disparate impact. A company uses an MBTI or DiSC test but never checks whether the test produces different outcomes by gender, race, or age. Disparate impact can exist without intent. If a test has not been monitored for impact, the employer cannot argue they checked and found it fair. Risk: discovery in litigation reveals unmonitored disparate impact, strengthening the plaintiff's case.
- Using a test designed for one purpose (e.g., coaching) as a hiring gate. A company buys MBTI for team-building, then uses the results to inform hiring decisions. MBTI was not designed or validated for hiring. Using it that way increases legal risk. Risk: plaintiff argues the company used an invalid assessment tool for employment purposes.
Best Practices to Minimize Legal Risk
1. Use tests that have job-related validation. Big Five is safer than MBTI for hiring because of published job-performance correlations. If using MBTI or DiSC, use them for coaching or team-building only, not hiring gatekeeping.
2. Monitor for disparate impact annually. Run statistics on your test scores and hiring outcomes by protected group (race, gender, age, disability). If a protected group passes at less than 80% of the majority group's rate, you have presumptive adverse impact. Either validate the test, change how you use it, or stop using it.
3. Document your validation study (or plan one). If you use a test as a hiring gate, run a validation study on your own workforce to show the test predicts performance in your environment. This is expensive but legally protective. Smaller companies often avoid this by using tests for non-gating purposes only (e.g., feedback, team-building).
4. Do not use test scores as the sole hiring gate. Use tests as one input among many (interviews, work samples, references). If a candidate is rejected, the reason should be multifactorial, not "they failed the personality test." This reduces the apparent importance of a single unvalidated tool.
5. Consult employment counsel. If you work in hiring and use personality tests, have an employment lawyer review your process. The cost of legal review is far lower than the cost of an EEOC complaint or settlement.
What This Means for Job Candidates
If you encounter a personality test in the hiring process, you should know: (1) the company has legal exposure if the test is unvalidated and produces adverse impact, (2) you cannot be rejected solely on personality type if the company follows best practices, and (3) personality tests are lower-stakes than skills assessments or work samples. If a company rejects you based solely on an MBTI type or an unvalidated personality test, you have grounds to question the decision. Reputable companies use personality tests to understand how you work, not to filter you out.
If you are preparing for personality assessments, focus on honest, thoughtful answers. Do not try to game the test by answering what you think the company wants. Personality tests are harder to fake than skills tests, and companies expect variation. What matters more is whether your skills and experience align with the role—use the Career Match assessment to ensure you are applying to roles where your actual strengths land. Taking a personality test you are wrong for is lower-risk than applying for a job that does not fit.
The Bottom Line
Personality tests are legal in hiring, but they are regulated. Tests without job-related validation are legally riskier when used as hiring gates. MBTI and DiSC are safest in coaching contexts. Big Five has research backing and is safer for hiring if monitored for disparate impact. Companies that use unvalidated tests as sole rejection criteria are exposing themselves to legal risk, especially if the tests produce disparate impact by protected group. If you work in hiring, validate before gating. If you are a job candidate, answer honestly and do not stress about personality tests—they are lower-stakes than skills assessments, and reputable employers know personality type is not destiny.
