Chapter 4: DUI / DWI Laws

Operating a motor vehicle while impaired by alcohol or drugs is one of the most dangerous decisions a driver can make, contributing to a significant percentage of fatal crashes. Maine has enacted some of the nation’s toughest Operating Under the Influence (OUI) laws to combat this threat. Understanding these laws, the concept of implied consent, and the severe penalties involved is critical for your safety, the safety of others, and for passing your knowledge exam.

OUI & Implied Consent

In Maine, it is a criminal offense to operate or attempt to operate a motor vehicle while under the influence of intoxicants or with an excessive blood alcohol concentration (BAC). This is known as OUI.

Defining “Under the Influence”

This applies to impairment from alcohol, any legal or illegal drug (including marijuana, prescription medication, or over-the-counter drugs), or a combination of substances. A driver can be convicted of OUI based on evidence of impaired driving ability, even if their BAC is below the legal limit.

Blood Alcohol Concentration (BAC) Limits

Maine has per se laws, meaning it is automatically illegal to drive with a BAC at or above a specific level, regardless of whether you appear impaired.

• 21 or Older: 0.08% or higher.
• Under 21: Any measurable amount of alcohol (0.00% BAC). This is Maine’s “Zero Tolerance” law.
• Commercial Vehicle Operators: 0.04% or higher while operating a commercial vehicle.

Implied Consent Law

When you operate a motor vehicle in Maine, you automatically give your consent to a chemical test (breath, blood, or urine) to determine your alcohol level or drug concentration. This is known as “Implied Consent.” A law enforcement officer must have probable cause to believe you are operating under the influence to request a test.