In the state of New Hampshire, the offense of drunk driving is referred to as "Driving or Operating Under the Influence" (DWI/DUI). Under New Hampshire law, it is illegal to drive or attempt to drive a vehicle or operate or attempt to operate an OHRV while under the influence of intoxicating liquor and/or any controlled drug (or a combination of such).

PER SE DWI - No person is permitted to drive or attempt to drive a vehicle or operate or attempt to operate an OHRV while the person has an alcohol concentration of .08 or more.

MINORS - Persons under the age of 21 will be charged with DWI/BWI if they have a blood alcohol content (BAC) of .02 or more.

BOATING WHILE IMPAIRED - New Hampshire also prohibits persons from Boating While Impaired (BWI). New Hampshire law prohibits any person from operating or attempting to operate a boat while under the influence of intoxicating liquor or a controlled drug or any combination of intoxicating liquor and a controlled drug or drugs, or while such person has an alcohol concentration of 0.08 or more (or in the case of persons under the age of 21, 0.02 or more).

COMMERCIAL DRIVERS - Any person who drives a commercial vehicle is prohibited from operating or driving a commercial vehicle with a BAC of .04 or more. It is illegal in New Hampshire to drive a commercial motor vehicle while having alcohol in your system. Any person who drives a commercial motor vehicle while having alcohol in his/her system, or who refuses to take a test to determine his or her alcohol concentration, will be placed out-of-service for 24 hours.

AGGRAVATED DWI - Persons arrested for DWI will be charged with aggravated DWI if any of the following instances occurred at the time of the alleged DWI offense:
1. Speeding 30 mph over the legal limit;
2. Causes an accident that results in serious bodily injury to the person or another;
3. Attempts to elude police pursuit by increasing speed, turning off headlamps, or boat navigation lamps while still in motion, or abandoning a vehicle, boat, or OHRV during pursuit;
4. Has a minor passenger under the age of 16 present in the vehicle at the time of the alleged offense; OR
5. Has a BAC of .16 or more.

FELONY DUI - A fourth offense DWI will be charged as a felony. In addition, any person who is arrested for a DWI offense following an accident where serious bodily injury or death results will be charged with a felony offense.