Can an Employer Require a Polygraph Test in California?

A staff member goes missing from the register. A shipment comes up short. Someone in HR starts asking who was in the building that night, and within a day, a manager mentions “polygraph” in a meeting. For the employee sitting across the table, the question isn’t about guilt yet. It’s simpler than that. Can an employer require a polygraph test in California, or is it fine to just say no?

For most private employers in California, the answer is no, and most employers don’t actually qualify for them. Here’s what the law says, what a 2025 California court decision just made painfully clear, and where a polygraph test still fits into a legitimate workplace investigation.

The Short Answer: Can an Employer Require a Polygraph Test in California?

California Labor Code Section 432.2 settles this quickly. No employer, outside of government agencies, can demand or require a polygraph, lie detector, or similar test from an employee or job applicant. That covers hiring decisions and continued employment alike. It isn’t a guideline. It’s a flat prohibition, on the books since 1963.

The law adds a second requirement most employers overlook. If an employer does administer a test, that employer must tell the employee, in writing, exactly what rights they have under this section before the test happens. Skip that notice, and the employer is already in violation, no matter what the test itself turns up.

An employee can still volunteer. Nothing in Section 432.2 stops someone from choosing to sit for a polygraph exam on their own, once they understand what they’re agreeing to. The line the law draws is coercion, not the test itself.

The Federal Law Every California Employer Still Has to Follow

Even outside California, most private employers hit the same wall at the federal level. The Employee Polygraph Protection Act of 1988, known as the EPPA, bars most private-sector employers nationwide from using lie detector tests on employees or applicants. That covers pre-hire screening and testing someone already on payroll alike. The U.S. Department of Labor enforces it. The penalties are real, too: injunctions, civil fines, and the employee’s own right to sue.

The EPPA does carve out a few narrow lanes. Security firms, including armored car, alarm, and guard companies, can polygraph certain applicants. So can pharmaceutical manufacturers and distributors, given the access their employees have to controlled substances. There’s also an “ongoing investigation” exception. Say an employer suffers a specific economic loss, like a theft or embezzlement, and has a reasonable, documented suspicion pointing at a particular employee. A polygraph can sometimes become part of that investigation. Even then, the examiner must be licensed and bonded, and strict pre-test and post-test rules apply throughout.

California employers have to clear both bars, state and federal, not just one. Section 432.2 doesn’t include the same theft-investigation exception the federal law allows. That leaves California businesses with even less room to work with than the EPPA alone would suggest.

When a Workplace Polygraph Actually Makes Sense

None of this puts a polygraph test off the table for employers. It means the process matters as much as the decision to use one. Picture a warehouse where inventory keeps coming up short, or a dealership missing cash from a single register that only three people can access. That’s the kind of specific, documented loss the law is actually built around. A properly administered, voluntary polygraph exam can be one legitimate tool inside that kind of investigation. It shouldn’t be the whole investigation on its own.

“Properly administered” carries a lot of weight in that sentence. It means a licensed examiner conducts the test, not an in-house manager with a rented machine. It means written notice of rights, delivered before the test, not after. It means documentation showing the specific economic loss and the reasonable basis for suspecting the person being tested, rather than a blanket policy applied to an entire department. It also means treating a refusal as what the law says it is: not grounds for termination or discipline on its own.

This is also where investigations tend to overlap in practice. A theft investigation that includes a polygraph often runs alongside record reviews and surveillance. Sometimes it folds into a broader workers’ compensation fraud investigation, especially when the loss traces back to a disputed injury claim rather than missing cash. Handled together, by investigators who know exactly where the legal lines sit, a polygraph stops being a liability risk. It becomes one investigative tool that can be considered alongside other evidence, documentation, interviews, and investigative findings, not the whole verdict.

What to Do If You’re Asked to Take One

If a manager or HR representative asks for a polygraph test in California, it’s fair to ask a few questions before answering. Is this actually voluntary, or is the employer treating it as a condition of keeping the job? Did the employer provide written notice of rights under Section 432.2? Is there a specific, documented economic loss behind the request, or is this just a blanket policy?

Saying no is allowed. In nearly every situation a private employer will face, refusing a polygraph test is protected. An employer cannot legally use that refusal as grounds for firing someone, disciplining them, or denying a promotion. When it happens anyway, the refusal itself can become the basis of a claim, the way it did in the McDoniel case.

None of this means every employer asking for a polygraph is acting in bad faith. Most workplace investigations start because something genuinely went wrong, and getting to the truth matters to everyone involved, not only the employer. The difference between a fair process and a legal problem usually comes down to a few basics: a licensed examiner, real notice, a documented reason. And a test that stays voluntary in practice, not only on paper.

Employers investigating a specific loss want to do it the right way. Employees want to understand their options before agreeing to anything. Excell Investigations has handled polygraph examinations for California businesses and individuals for years, for exactly these situations. Its licensed examiners know where Section 432.2 draws the line, and the same team also handles polygraph testing for personal and legal matters outside the workplace. Request a polygraph test and talk to an examiner before the situation gets more complicated than it needs to be.