Home › Workplace drug testing laws › Missouri
Missouri drug testing laws for employers
Missouri has no general drug testing law for private employers. Adult-use and medical marijuana are both legal under the state constitution, and medical card holders have protection from action based only on their status or a positive test, with exceptions for jobs where use affects safety or job duties. A clear written drug policy matters for workers' comp and unemployment.
Have a whole roster to keep current every month? DOT fleets: Pact's monthly DOT program, $25 a driver a month ($99 minimum), or $19 a month for an owner-operator. Nursing homes, hospice and home care: staff credential tracking, $10 a staff member a month ($250 minimum). First month free.
The state law
- We found no Missouri statute that sets testing rules for all private employers (no statute found).
- The unemployment law has its own testing rules that apply only if you want a positive test to count as misconduct for unemployment (RSMo 288.045.9).
- For that unemployment rule, your policy must be posted or in a handbook and must say a positive test may lead to suspension or firing (RSMo 288.045.3).
- For that unemployment rule, collection must follow DOT 49 CFR Part 40 chain-of-custody procedures and the lab must be HHS-certified or meet HHS standards (RSMo 288.045.2 and .6).
- For that unemployment rule, a policy started after January 1, 2005 needs at least 60 days' notice to all employees before it takes effect (RSMo 288.045.10).
Testing applicants
- We found no state law that limits applicant testing by private employers (no statute found).
- You may require a pre-employment test, and the result counts for unemployment if the person was told about the test beforehand (RSMo 288.045.4).
Random testing
- We found no state law that limits random testing by private employers (no statute found).
- A random test result counts for unemployment only if your policy clearly says employees may be randomly tested (RSMo 288.045.4).
Marijuana (recreational)
- You may not penalize a medical card holder for their status or for legal off-duty use off your premises, unless they were under the influence at work or during work hours (Mo. Const. Art. XIV, Section 1.7(15)(a)).
- You may not penalize a medical card holder for a positive marijuana test alone, unless they used, possessed or were under the influence at work or during work hours (Mo. Const. Art. XIV, Section 1.7(15)(b)).
- These card holder protections do not apply to jobs where legal use affects the person's ability to do the job or the safety of others, or conflicts with a bona fide occupational qualification (Mo. Const. Art. XIV, Section 1.7(15)).
- The protections also do not apply if following them would cost you a monetary or licensing benefit under federal law (Mo. Const. Art. XIV, Section 1.7(15)).
- A worker cannot sue you for barring them from being under the influence at work or for disciplining them for working under the influence (Mo. Const. Art. XIV, Section 1.7(1)(d)).
- The adult-use law does not make you allow marijuana at work and lets you refuse to hire, discipline or fire someone for working under the influence (Mo. Const. Art. XIV, Section 2.3(3)).
Also good to know
- Workers' comp benefits are cut 50% if an injury happened in connection with alcohol or non-prescribed drug use that broke your drug-free workplace rule or policy (RSMo 287.120.6(1)).
- Workers' comp benefits are forfeited if that alcohol or drug use was the main cause of the injury (RSMo 287.120.6(2)).
- Refusing an employer's alcohol or drug test forfeits workers' comp benefits if you had cause to suspect use or your policy clearly allows post-injury testing (RSMo 287.120.6(3)).
- A positive test creates a presumption for workers' comp only if the test was within 24 hours of the injury, results were shared on time, and the worker could retest the original sample (RSMo 287.120.6(4)).
- Being at work with alcohol or a controlled substance in your system in violation of the employer's policy is misconduct for unemployment purposes (RSMo 288.045.1).
- For unemployment purposes, an employee may ask for a split-specimen confirmation test at a separate lab and pays only if it confirms the positive (RSMo 288.045.7).
Common questions
Is drug testing legal for employers in Missouri?
Missouri has no general drug testing law for private employers. Adult-use and medical marijuana are both legal under the state constitution, and medical card holders have protection from action based only on their status or a positive test, with exceptions for jobs where use affects safety or job duties. A clear written drug policy matters for workers' comp and unemployment.
Can employers in Missouri test applicants before hiring?
We found no state law that limits applicant testing by private employers (no statute found).
Is random drug testing allowed in Missouri?
We found no state law that limits random testing by private employers (no statute found).
Can a Missouri employer act on a positive marijuana test?
You may not penalize a medical card holder for their status or for legal off-duty use off your premises, unless they were under the influence at work or during work hours (Mo. Const. Art. XIV, Section 1.7(15)(a)).
Some rules for Missouri weren't confirmed from an official source. Check with the state before relying on this page.
Sources
- Mo. Const. Art. XIV, Section 1 (official)
- Mo. Const. Art. XIV, Section 2 (official)
- RSMo 287.120 (official)
- RSMo 288.045 (official)
This page summarizes state law in plain words, with links to the law itself. It is not legal advice, and laws change: check the linked source, and talk to a lawyer about your own policy. Federal DOT testing rules are separate and override state limits for DOT-covered jobs. Checked October 2026.