Drug Testing Laws in Missouri

State law (Missouri): The section does not require an employer to permit or accommodate conduct otherwise allowed by it in any workplace or on the employer's property Source 1State legislatureMo. Const. art. XIV §2 — adult use marijuana; employer provisions — checked 18 Aug 2026.

Employer policy: Missouri has no general private-sector drug testing statute that we identified, so panels, cutoffs, confirmation and consequences come from the employer's written policy. That is an absence in our research rather than a statutory declaration that no rules exist.

State law (Missouri): Two permissions, both tied to the same condition. The section does not prohibit an employer from disciplining an employee for working while under the influence of marijuana Source 1State legislatureMo. Const. art. XIV §2 — adult use marijuana; employer provisions — checked 18 Aug 2026. And it does not prevent an employer refusing to hire, discharging, disciplining or otherwise taking adverse action with respect to hire, tenure, terms, conditions or privileges of employment because that person was working while under the influence Source 1State legislatureMo. Const. art. XIV §2 — adult use marijuana; employer provisions — checked 18 Aug 2026.

That qualifier is doing real work and most summaries drop it. Every employer permission in the section is anchored to working while under the influence — not to off-duty use, and not to the presence of a metabolite in a sample.

We are not going to tell you what follows from that, because the constitution does not say. It contains no express protection for lawful off-duty use, and no express authorisation to act on a metabolite-only result. If your situation turns on that gap, it is a question for a Missouri employment lawyer, not for this page.

State law (Missouri): No safety-sensitive carve-out and no federally regulated carve-out appears in this section Source 1State legislatureMo. Const. art. XIV §2 — adult use marijuana; employer provisions — checked 18 Aug 2026 — unlike Washington and Nevada, which enumerate excluded roles at length.

State law (Missouri): A related provision preserves existing laws prohibiting conduct that endangers others, and laws on negligence, recklessness and professional malpractice Source 1State legislatureMo. Const. art. XIV §2 — adult use marijuana; employer provisions — checked 18 Aug 2026. That is not a testing rule, but it is where a safety argument in Missouri would be anchored.

Federal (DOT): Because the section has no federal carve-out, it is worth stating plainly: it does not need one. Federal rules govern a DOT-regulated test regardless, marijuana is on the federal panel, and a state constitutional provision does not reach it.

Not verified here: Missouri's medical cannabis employment provisions, which sit in a different constitutional section that we have not read. If you are a registered patient, do not read this page as describing your position.