If you boat around Tampa Bay or the Gulf beaches, the agency that stops you may not be a local one. The United States Coast Guard works the same water as the Florida Fish and Wildlife Conservation Commission and the county marine units, and boating under the influence is a federal offense under 46 U.S.C. 2302, not only a state charge. Most cases still land in state court under section 327.35, but the Coast Guard is often the agency that makes the first stop, runs the exercises, and builds the file the State later uses. Knowing how a federal boarding works, and where its limits are, is part of defending the case that follows.
The Coast Guard can board your boat without any reason
This is the part that surprises many folks. On the water, the Coast Guard does not need probable cause or even reasonable suspicion to stop and board your vessel for a documentation and safety inspection. The Supreme Court said so in United States v. Villamonte-Marquez, 462 U.S. 579 (1983), and Florida courts follow it. Arguing that the boarding itself was unlawful almost never works.
What the boarding does not do is hand the officers a blank check. It is a brief inspection: they come aboard, look at public areas, and check your papers and equipment. Going further, into a full search or a held detention to run sobriety exercises, takes reasonable suspicion built on something real, not just the fact of the stop. That boundary, between a lawful safety inspection and an investigation that outran it, is the same pressure point that runs through every BUI case, and it is where a motion to suppress lives.
Two standards: the number and the behavior
The Coast Guard judges impairment two ways at once. There is a blood-alcohol standard, measured in the field with a handheld unit, and a separate behavioral standard based on what the boarding officer sees and how you perform the exercises. The authorized field device is the ALCO Sensor III, a small handheld breath tester. It is a screening tool. It is not the evidentiary instrument that produces a courtroom-quality reading, and treating a handheld screen as proof of a number is one of the first things I look at.
The behavioral standard is just as attackable, because it rests on the boarding officer’s read of you in a setting built to make a sober person look impaired.
Sun, wind, and sea legs do the State’s work
The Coast Guard’s own training describes the environmental stressors of being on the water: sun, wind, glare, vibration, and the noise of the craft and the water, all of which affect balance, depth perception, and the ability to track moving objects. The materials say these stressors hit an operator from the first sip of alcohol, and that cuts both ways. The same sun and wind and motion produce flushed skin, bloodshot and watery eyes, and unsteady balance in a boater who has had nothing to drink. Add sea legs after hours on a rocking deck, and you have the exact signs the officer is trained to score as intoxication.
On top of that, the exercises are not the validated roadside set. They are the seated battery built for a boat, and as an NHTSA-qualified field sobriety instructor I challenge how they were chosen, administered, and scored, and the leap from a few imperfect movements to an opinion that you were impaired.
Federal implied consent and the $5,000 penalty
The Coast Guard runs its own implied-consent system. You are told that refusing the test can terminate the voyage, will be used against you, and lets the officer presume you were intoxicated. A refusal carries a federal civil penalty of up to $5,000 under 33 C.F.R. subpart 1.07, decided by a Coast Guard hearing officer, and you have thirty days to respond or to ask for a hearing. The Coast Guard also treats reasonable suspicion plus a refusal as probable cause to arrest. None of this replaces the state side: if your case becomes a Florida BUI, the state refusal rules and the $500 state civil penalty apply on their own track.
From a federal stop to a state charge
In practice, the Coast Guard rarely prosecutes a recreational BUI itself. It hands the operator to the Florida Fish and Wildlife Conservation Commission or the county sheriff, and the case is charged under section 327.35 in state court. That matters for your defense, because the evidence gathered during a federal boarding, the handheld reading, the seated exercises, the officer’s observations, all of it has to stand up under Florida law once the case is in state court. The federal civil penalty and the state criminal case can run at the same time, and both deserve a response.
I started out as an Assistant Public Defender in Florida’s Thirteenth Judicial Circuit, in Tampa, and today I am one of six ACS-CHAL Forensic Lawyer-Scientists in Florida and an NHTSA-qualified field sobriety instructor. A BUI puts the stop, the exercises, and the testing all in play at once, which is the exact ground I work on every day. I can give you a straight read on whether your case is a suppression fight, a reduction to a boating infraction, or a trial. Learn more about my background.
Related: the main boating under the influence page, field sobriety, breath test, blood test, and search and seizure.
Coast Guard and federal BUI questions
Can the Coast Guard stop my boat without any reason?
Yes. The Coast Guard can board a vessel to check documents and safety equipment without any suspicion that a crime is occurring, and courts have upheld that authority. The catch is that the boarding is a brief, limited inspection. Once it turns into a search or a sobriety investigation, the officers need more, and that is where many cases are challenged.
Is BUI a federal crime?
It can be. Operating a vessel while impaired is a federal offense under 46 U.S.C. 2302, and the Coast Guard enforces it on the water. Most Florida BUI cases are still prosecuted in state court under section 327.35, because the Coast Guard usually hands the operator to the Florida Fish and Wildlife Conservation Commission or the local sheriff, but a federal civil penalty and a state criminal case can both follow from the same stop.
What happens if I refuse the Coast Guard's test?
The Coast Guard uses its own implied-consent rule. A refusal can be treated as a presumption of intoxication, is admissible against you, and carries a federal civil penalty of up to $5,000 under 33 C.F.R. subpart 1.07. You have thirty days to respond or request a hearing before a Coast Guard hearing officer. Refusing on the water does not make the state refusal consequences go away either.
What device does the Coast Guard use to measure alcohol?
The authorized field unit is the ALCO Sensor III, a handheld breath tester. The Coast Guard runs two separate standards: a blood-alcohol number from the device, and a behavioral standard based on the seated field sobriety exercises and what the boarding officer observes. Both can be challenged, and the handheld reading in particular is a screening tool, not a substitute for an evidentiary breath test.
The Coast Guard stopped me, so why is my case in state court?
Because the Coast Guard typically refers the operator to the Florida Fish and Wildlife Conservation Commission or the county sheriff for prosecution under section 327.35. The federal stop is often where the evidence is gathered, but the criminal case is litigated in state court, which is where the stop, the exercises, and the testing get fought.
This page is general information about Florida law, not legal advice, and it does not create an attorney-client relationship. Boating under the influence is governed by section 327.35 and related sections of chapter 327, Florida Statutes, and the Coast Guard’s boarding authority and the federal boating-while-intoxicated penalties come from federal law, including 46 U.S.C. 2302 and 33 C.F.R. subpart 1.07. Charge reductions and program eligibility are decided by each prosecutor at sole discretion and can change at any time. Every case turns on its own facts, and past results do not guarantee a similar outcome.
