Drugs, Alcohol & DUI: Details & Regulations

By Captain Mike · 50 years at sea · former MITAGS faculty
Checked against 46 CFR Parts 4, 10 and 16, 33 CFR Part 95 and 49 CFR Part 40 · September 2026

Before you apply
This page provides general educational information for prospective and current U.S. merchant mariners. It is not legal advice, medical advice, drug-testing advice, employment advice, or an official U.S. Coast Guard eligibility determination. Requirements change. Always check the current National Maritime Center instructions and regulations before acting.

This is the companion to Drugs, Alcohol, DUI & Your Coast Guard Credential. Start there if you haven't read it. This page holds the regulatory detail for readers who need it.

DUI and the National Driver Register

Applicants for an original or reissued MMC, or a new officer endorsement, must consent to a National Driver Register (NDR) check. The Coast Guard applies these assessment guidelines to alcohol- and drug-related driving convictions 46 CFR 10.213:

Drug/alcohol driving convictions	General guideline
One, less than 1 year old	Wait 1 year from the conviction date
One, 1 to 3 years old	Generally processed, unless a suspension or revocation is still in effect
One, more than 3 years old	Generally processed
Two or more, at least one less than 3 years old	1 year since the latest and at least 3 years since the second most recent
Two or more, all more than 3 years old	Generally processed, unless a suspension or revocation is still in effect

These are guidelines, not guaranteed outcomes. Criminal convictions, drug-use history, rehabilitation and other suitability factors can change the evaluation. Check the live regulation before you rely on the table.

Your driving record gets checked too

When you apply, the Coast Guard reviews the National Driver Register, which lists license suspensions, revocations and serious offenses such as DUI. An old suspension in another state, including one caused by an unpaid ticket or an administrative action you've forgotten about, can hold up your safety and suitability review. The NMC may ask for your driving record or certified court dispositions before it can finish. Check your record in every state where you've held a license, and clear up anything open, before you apply.

Dismissed, reduced, deferred or expunged

The Coast Guard's definition of a conviction can be broader than you expect. Depending on the facts, no-contest pleas, deferred adjudication, probation or treatment conditions, and some diversion arrangements may count, and an expungement doesn't necessarily remove an offense from consideration. On the other hand, an arrest that didn't lead to a conviction shouldn't be reported as one. Get the actual court disposition and your driving record, and answer each question exactly as written.

What the safety and suitability review can draw on

The Coast Guard may review an applicant's criminal record to judge safety and suitability 46 CFR 10.211. Sources can include:

TSA/TWIC recordsFBI criminal historyNational Driver RegisterEarlier applications and disclosuresDocuments you submit

It may also consider completed treatment, demonstrated rehabilitation, steady employment, character references, and completion of court-ordered conditions.

Drug testing: three separate tracks

Situation	What to know
Your MMC application	Many credential transactions require proof of a passed DOT/USCG drug test, or acceptable documentation from an employer's testing program.
Working for a marine employer	Pre-employment, random, reasonable-cause, post-incident, and return-to-duty and follow-up testing, plus whatever the company's policy adds.
Your credential	A verified positive or a refusal can affect your job and your Coast Guard credential. Those are related but separate processes.

Testing follows DOT procedures in 49 CFR Part 40. The Coast Guard sets the minimum random-testing rate each year; for 2026 it is 50% of covered crewmembers 46 CFR 16.230. That's a program-wide rate, so an individual can be selected more than once.

Alcohol rules in detail

On inspected vessels and vessels subject to inspection, a crewmember may not perform or attempt to perform scheduled duties within four hours of consuming alcohol, be intoxicated at any time, or consume intoxicants while on watch or duty 33 CFR 95.045. For commercial vessels, an alcohol concentration of 0.04 or more in the blood or breath is one standard for being under the influence, and observed impairment can establish a violation below that level 33 CFR 95.020.

If a mariner fails a drug test

A credentialed mariner who fails a required chemical test for dangerous drugs must be removed from duties that directly affect vessel safety as soon as practicable, the result is reported to the Coast Guard, and the mariner is subject to suspension and revocation proceedings 46 CFR 16.201. No marine casualty has to be involved.

Returning to safety-sensitive duty involves a professional evaluation, evidence of rehabilitation, a return-to-duty decision by a Medical Review Officer, and at least six unannounced follow-up tests in the first year, with follow-up testing that can continue up to 60 months. The Coast Guard credential case is a separate matter that also has to be resolved.

Refusals. Under DOT rules a refusal to test is treated like a positive, and it carries its own credential consequences.

Serious marine incidents

After a serious marine incident, chemical testing can extend beyond the person at the helm to crewmembers directly involved in the incident 46 CFR 4.06. Saving lives and securing the vessel come first. Alcohol testing is generally required within 2 hours and drug specimens within 32 hours, unless safety concerns prevent it.

When to get individualized help

Get your official records first, then consult current NMC guidance and, when appropriate, a maritime licensing professional, attorney, treating clinician, Medical Review Officer, employer or testing consortium, if you have:

A DUI, drug-impaired-driving conviction, reckless-driving record, current suspension, or revocation
More than one alcohol- or drug-related driving incident
A criminal conviction, deferred disposition, diversion agreement, probation, or unresolved charge
A previous positive DOT/Coast Guard drug test, refusal to test, or return-to-duty issue
A history involving dangerous drugs or substance-use treatment
Prescription medication or a medical condition that could affect safety-sensitive duties
Uncertainty about how to answer a question on the CG-719B or another Coast Guard form

See Need Professional Help?

Your record requires an individual review

A past DUI, criminal conviction, drug-related matter, prior test result, prescription medication, or driving-record issue does not automatically mean you cannot become a mariner. It may, however, affect timing, documentation, safety-and-suitability review, credential issuance, renewal, or employment.

Mariners Online cannot determine your eligibility. Read the current Coast Guard application carefully, answer every question truthfully, obtain official records, and consult current NMC guidance or qualified individualized advice before applying if your history is complicated.