A Merchant Mariner Credential, or MMC, is the document the United States Coast Guard issues to people who work as officers, ratings, or other qualified crew aboard covered vessels. Before the Coast Guard issues, reissues, or upgrades an MMC, it runs its own safety and suitability review of the applicant. That review is separate from anything a marine employer does on its own, and it looks at three main things: criminal convictions, certain motor vehicle and alcohol or drug related driving convictions reported through the National Driver Register, and results of required drug testing. Employers who hire mariners generally still need to run their own pre employment screening on top of the credentialing process, because the MMC review answers only whether the Coast Guard will issue the credential, not whether a particular applicant is right for a particular job.
This post walks through what the Coast Guard actually reviews under 46 CFR 10.211 and 46 CFR 10.213, how drug testing under 46 CFR Part 16 and 49 CFR Part 40 fits into the credentialing picture, why a Transportation Worker Identification Credential is part of the process, and where employer screening picks up.
The criminal record review
Under 46 CFR 10.211, the Coast Guard may conduct a criminal record review to decide whether an MMC applicant is a safe and suitable person to hold the credential. Every applicant must disclose, in writing, any prior convictions not already on file with the Coast Guard. The Coast Guard does not run this check independently from scratch. Under the regulation, the Transportation Security Administration provides the applicant’s FBI number and criminal history record, generated during the Transportation Worker Identification Credential review, to the Coast Guard for this purpose. In other words, the criminal background portion of the MMC evaluation is built on top of the same fingerprint based check that produces a TWIC.
If the review shows the Coast Guard cannot be satisfied the applicant is safe and suitable, or cannot be entrusted with the duties of the credential or endorsement applied for, the application may be denied. A denied applicant is notified in writing of the reason for denial and of the reconsideration and appeal rights in subpart 1.03 of 46 CFR part 1.
Assessment periods by offense category
The regulation does not treat every conviction the same way. Instead, it sets minimum and maximum assessment periods for categories of crimes, counted from the date the applicant is no longer incarcerated. If an applicant applies before the minimum period has run, the applicant must submit evidence of suitability for the Coast Guard to consider. If the applicant applies between the minimum and maximum periods, the Coast Guard generally grants the credential unless offsetting factors are present, such as multiple convictions or a clear connection between the crime and safe operation of a vessel. After the maximum period has run, the Coast Guard generally grants the credential unless it still finds the applicant unsuitable. The categories below are exactly what 46 CFR 10.211 publishes as Table 1; the regulation is explicit that this list is a guide and not exhaustive, and that offenses not listed are assigned an appropriate period using the table as a reference.
| Offense category | Minimum assessment period | Maximum assessment period |
|---|---|---|
| Homicide, intentional | 7 years | 20 years |
| Homicide, unintentional | 5 years | 10 years |
| Assault, aggravated | 5 years | 10 years |
| Assault, simple | 1 year | 5 years |
| Sexual assault (rape, child molestation) | 5 years | 10 years |
| Robbery | 5 years | 10 years |
| Vehicular conviction involving fatality | 1 year | 5 years |
| Reckless driving | 1 year | 2 years |
| Racing on the highways | 1 year | 2 years |
| Destruction of property | 5 years | 10 years |
| Drug trafficking (sale, distribution, transfer) | 5 years | 10 years |
| Dangerous drug use or possession | 1 year | 10 years |
| Environmental law violation involving pollutants or hazardous materials (officer endorsements only) | 1 year | 10 years |
| Burglary | 3 years | 10 years |
| Larceny or embezzlement | 3 years | 5 years |
A conviction for a dangerous drug offense more than 10 years before the date of application is not, by itself, grounds for denial, though the regulation allows the Coast Guard to consider an older drug conviction if there has been another one within the past 10 years. When an applicant has more than one conviction, the Coast Guard applies the longest minimum and longest maximum period among the convictions. No person who has ever used or been addicted to a dangerous drug is eligible for an MMC unless they provide satisfactory evidence of rehabilitation, which can include proof of completion of an accredited treatment program, active participation in a recognized recovery group, character references, steady employment, and successful completion of any probation or parole conditions.
The National Driver Register check
Separate from the criminal record review, 46 CFR 10.213 requires every applicant for an original or reissued MMC, and for any new officer endorsement, to consent to a check of the National Driver Register. That check looks specifically for offenses described in the National Driver Register Act: operating a motor vehicle while under the influence of, or impaired by, alcohol or a controlled substance, and traffic violations connected to a fatal accident, reckless driving, or racing on the highways. The Coast Guard generally will not consider a National Driver Register listed civil conviction more than 3 years old unless it relates to a current license suspension or revocation, and it evaluates drug or alcohol related driving convictions using a separate table based on the number of convictions and how recent they are. A single conviction less than a year old carries a 1 year assessment period from the date of conviction, while two or more convictions within 3 years generally require at least 1 year since the most recent conviction and at least 3 years from the second most recent, unless a license suspension or revocation is still in effect. Before denying an application based on National Driver Register information, the Coast Guard must give the applicant a chance to review the information and respond in writing, and the applicant may submit state driving records to support their case.
Drug testing under 46 CFR Part 16 and 49 CFR Part 40
Chemical testing for merchant mariners is governed by 46 CFR Part 16, which requires testing under circumstances including pre employment, periodic (tied to issuance, upgrade, or reissuance of a credential), random, reasonable cause, and post serious marine incident. The actual testing procedures, chain of custody, laboratory certification, and review steps come from 49 CFR Part 40, the Department of Transportation’s uniform drug and alcohol testing rule that applies across DOT regulated transportation modes. This is where the distinction between an initial screening test and a confirmation test matters. A urine specimen is first screened using an immunoassay method, which is fast and sensitive but not specific enough on its own to confirm a positive result. Any specimen that screens positive on the initial test must be confirmed using a more specific method, typically gas chromatography or mass spectrometry, at a certified laboratory, before it can be reported as a verified positive.
Even a confirmed positive laboratory result does not automatically become a reportable “positive” test. Under 49 CFR Part 40, a Medical Review Officer, a licensed physician trained in this review process, examines the confirmed result and any legitimate medical explanation the individual provides, including current prescriptions, before verifying the test as positive or negative. This is why the process depends on documentation: a mariner taking a legitimately prescribed medication that could otherwise trigger a screening positive needs to be prepared to provide that prescription information to the Medical Review Officer during the verification interview. Under 46 CFR 16.201, an individual who fails a required chemical test for dangerous drugs is presumed to be a user of dangerous drugs, must be removed from safety sensitive duties, and if the individual holds a credential, the employer must report the result in writing to the nearest Coast Guard Officer in Charge, Marine Inspection. Before returning to work, the Medical Review Officer must determine the individual is drug free and that the risk of future use is low enough to justify return, and the individual must submit to a minimum of six unannounced follow up tests in the first year back, with the possibility of continued testing for up to 60 months.
The TWIC prerequisite
A Transportation Worker Identification Credential is a Transportation Security Administration issued biometric card required for unescorted access to secure areas of maritime facilities and vessels regulated under the Maritime Transportation Security Act. As noted above, the criminal history information the Coast Guard uses in its MMC safety and suitability review is generated during the TWIC vetting process, so most mariners will go through TWIC screening either before or alongside their MMC application. Because TWIC and MMC eligibility both depend in part on criminal history, an issue that affects one, such as a disqualifying offense, can affect the other. Reveal Background has covered how TWIC disqualifying offenses and the appeal process work in more detail in this related post.
How employer screening differs from the Coast Guard’s review
The Coast Guard’s safety and suitability determination decides whether a person may hold an MMC at all. It does not replace, and is not replaced by, a maritime employer’s own pre employment screening. Employers hiring mariners, whether for deep sea vessels, towing, offshore supply, or inland operations, generally still need to verify the applicant’s identity, confirm the credential is current and matches the endorsements the job requires, and run their own background check consistent with the Fair Credit Reporting Act when a third party consumer reporting agency is used. That means a standalone disclosure, written authorization from the applicant, and, if the employer intends to take an adverse action based in whole or part on the report, a pre adverse action notice with a copy of the report and a summary of rights, followed by an adverse action notice if the employer proceeds. What a background check actually surfaces depends on the record sources searched and state law, and it does not necessarily duplicate what the Coast Guard already reviewed for the credential itself. Employers should not assume a valid, current MMC means an applicant has no history relevant to a specific role, since the two reviews serve different purposes and use different information.
Employers building a maritime or broader transportation hiring program can review Reveal Background’s overview of choosing a pre employment drug test panel for context on how screening decisions for safety sensitive transportation roles are typically structured.
Frequently asked questions
Does a Merchant Mariner Credential background check replace an employer’s own background check?
No. The Coast Guard’s review determines whether the applicant may hold the credential. Employers generally still need to run their own screening, including FCRA required disclosures and notices when a consumer reporting agency is used, to make a hiring decision for a specific role.
How far back does the Coast Guard look at criminal convictions?
The look back period depends on the offense category and follows the minimum and maximum assessment periods published in 46 CFR 10.211. Some categories carry a maximum assessment period as short as 2 years and others as long as 20 years, and the rule varies by the nature of the crime, so it is worth reviewing the primary source for the specific offense at issue.
What is the difference between a screening drug test and a confirmation test?
An initial immunoassay screening test flags specimens that may be positive, but it is not specific enough to confirm a result on its own. Any non negative screen must go to a confirmation test using a more specific laboratory method before a Medical Review Officer can verify it as positive.
Can a prescription medication cause a false positive on a mariner drug test?
Certain prescribed and over the counter medications can trigger a non negative result on an initial screening test. That is why the Medical Review Officer reviews confirmed results and any legitimate medical explanation, including current prescriptions, before verifying a test as positive or negative under 49 CFR Part 40.
Is a TWIC required to get a Merchant Mariner Credential?
TWIC and MMC eligibility are connected because the criminal history record the Coast Guard uses for the MMC safety and suitability review is generated during the TWIC vetting process. Most mariners go through TWIC screening as part of, or alongside, the MMC application process.
Does a dangerous drug conviction permanently bar someone from holding an MMC?
Not automatically. A conviction more than 10 years old is not by itself grounds for denial unless there has been another dangerous drug conviction within the past 10 years, and applicants may submit evidence of rehabilitation for consideration under the regulation.
Employers that need to build compliant screening into a maritime or broader transportation hiring program can see how Reveal Background supports that work on the transportation screening page.
This article is general information, not legal or medical advice. Screening and credentialing rules vary and can change, so employers and applicants should confirm current requirements with the applicable primary source or qualified counsel.
