Operating a boat while impaired by alcohol or drugs isn’t just dangerous — it’s illegal. Boating Under the Influence (BUI) laws are enforced in every U.S. state, and penalties can be just as severe as those for driving under the influence (DUI). But how do officers determine impairment on the water, where traditional field sobriety tests may not apply?
This guide explains how BUI is detected, what field sobriety tests look like on the water, and how enforcement differs from land-based DUI stops.
⚖️ What Is BUI?
Boating Under the Influence (BUI) refers to operating a vessel while impaired by alcohol, drugs, or a combination of both. It applies to:
- Motorboats and jet skis
- Sailboats (even under sail)
- Kayaks, canoes, and paddleboards in some states
Most states set the legal blood alcohol concentration (BAC) limit at 0.08%, the same as for motor vehicles. However, enforcement can begin well below that threshold if impairment is observed.
🚨 How BUI Is Enforced
BUI enforcement is typically handled by:
- State marine patrols
- Local law enforcement
- U.S. Coast Guard (especially in federal or coastal waters)
Officers may stop a vessel for any lawful reason — including equipment checks or observed violations — and initiate a BUI investigation if they suspect impairment.
🧪 Field Sobriety Tests on the Water
Unlike roadside DUI stops, traditional field sobriety tests (FSTs) are difficult to perform on a moving or unstable boat. That’s why officers often use seated field sobriety tests designed specifically for marine environments.
Common Seated FSTs Include:
- Horizontal Gaze Nystagmus (HGN): The officer checks for involuntary eye movement as the subject follows a stimulus (like a pen or finger).
- Finger-to-Nose Test: The subject touches the tip of their nose with alternating fingers while seated, eyes closed.
- Palm Pat Test: The subject alternates patting one hand with the other, flipping and increasing speed on command.
- Counting or Reciting: The subject may be asked to count backward or recite part of the alphabet.
These tests are designed to detect coordination issues, divided attention problems, and other signs of impairment — even while seated.
🧍♂️ Transition to Land-Based Testing
If impairment is suspected, officers may escort the boater to shore for:
- Standardized field sobriety tests (SFSTs) like the walk-and-turn or one-leg stand
- Breathalyzer or blood tests to determine BAC
- Drug recognition evaluations if drug use is suspected
Refusing these tests can result in penalties, including license suspension, fines, or arrest — depending on state law.
⚠️ Legal Consequences of BUI
Penalties for BUI vary by state but often include:
- Fines and court costs
- Jail time (especially for repeat offenses or accidents)
- Boating license suspension or revocation
- Mandatory substance abuse education
- Criminal record
If the BUI results in injury or death, felony charges may apply — with significantly harsher consequences.
🧠 Final Thoughts: Know the Signs, Know the Stakes
Boating under the influence puts everyone on the water at risk — and the legal consequences are serious. Field sobriety tests on the water may look different than those on land, but they’re just as effective at identifying impairment.
If you’ve been charged with BUI or injured by an impaired boater, consult a boat accident attorney who understands both maritime law and state-specific BUI enforcement. Legal guidance can protect your rights and help you navigate the complex aftermath of a boating incident.