Most flag states and most operators apply a strict alcohol limit (typically 0.05% blood alcohol or zero on duty) and a zero-tolerance illicit-drug policy. STCW Code Section A-VIII/2 requires watchkeepers to be free from impairment from drugs or alcohol. Random and 'for cause' testing is permitted under most operators' SMS and most CBAs. A positive test is normally grounds for immediate repatriation at the seafarer's cost, possible CoC suspension, and reporting to the flag state. If you take prescription medication, declare it in advance and carry the prescription.
Step-by-step
Check the company's drug and alcohol policy on joining: it will be in the SMS manual and referenced in the SEA. Note the testing procedures, declared limits, and 'reasonable suspicion' triggers.
Declare any prescription medication on the medical fitness form before joining. Carry the original prescription. Some medications (e.g. opioid analgesics, stimulants for ADHD, codeine) have flagged status in some jurisdictions.
If selected for random testing: cooperate fully. Refusal is treated as a positive result under most operator policies. Request that the test be conducted under the SAMHSA or equivalent chain-of-custody protocol with a split B-sample retained.
If you test positive: the company will normally repatriate immediately at your cost. Request a copy of the laboratory report, the chain of custody, and a confirmatory analysis of the B-sample at an accredited lab.
Contact your union or an ITF inspector. CBAs vary on whether positive results trigger automatic dismissal vs assistance into rehabilitation. Some CBAs (notably Nordic and Australian) require employer-funded rehabilitation as the first response.
STCW Reg. I/2 grounds for revocation of CoC are flag-state determined. A positive test is reportable to the flag state; you have due-process rights before any CoC action.
Evidence to save
Company SMS extract showing the policy + testing protocol
Original PEME + any prescription documentation
Test result lab report + chain-of-custody form
Communication with master / DPA about the testing decision
What NOT to sign
Test result without a chain-of-custody B-sample retained
Resignation 'in lieu' of a disciplinary hearing without union representation
Repatriation-at-your-cost acknowledgement without confirming the test was conducted to SAMHSA standard
Legal basis
STCW Code Section A-VIII/2 Part 5 (fitness for duty). ILO MLC 2006 Standard A4.3 (on-board safety). OCIMF Guidelines for the Control of Drugs and Alcohol Onboard Ship. SAMHSA-aligned chain-of-custody procedures are the industry-standard testing protocol. National laws (Norway, UK, US, Australia) impose criminal liability for operating a vessel impaired.
Disclaimer. General information only — not legal advice. Rules vary by flag state, port state, vessel type, applicable CBA, and contract. For specific cases, contact ITF, ISWAN, your union, or a maritime lawyer.