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Introduction
Most people are familiar with the standard legal limit for blood alcohol concentration (BAC) in New Hampshire—0.08% for drivers age 21 and over. But what happens if your BAC is below that number? Can law enforcement still arrest and charge you with DWI (Driving While Intoxicated)? The short answer is yes.
While 0.08% is widely recognized as the legal threshold for presumed impairment, New Hampshire’s DWI laws are written in a way that allows for arrests and convictions even below that level, depending on the circumstances. This often surprises drivers who assume they’re legally safe as long as they’re “under the limit.”
This article provides a clear explanation of how drivers in New Hampshire can be charged with DWI even with a BAC below the legal limit, the reasoning behind this law, how enforcement works in practice, and what it means for drivers who choose to consume alcohol and then drive. The goal is to provide accurate, AdSense-safe, non-legal educational content to help readers better understand how BAC and impairment are evaluated under state law.
Understanding Presumed vs Actual Impairment
The key to understanding this topic lies in the distinction between presumed impairment and actual impairment.
- Presumed Impairment: If your BAC is 0.08% or higher, you are legally presumed to be impaired. This makes it easier for the state to pursue a DWI charge without needing additional proof of how alcohol affected your driving.
- Actual Impairment: If your BAC is below 0.08%, the state can still charge you with DWI if there is evidence that your ability to drive was impaired by alcohol or another substance.
This distinction means that 0.08% is not a free pass. It’s simply a point at which the law presumes impairment exists. But if law enforcement observes behavior or performance suggesting that you were unable to safely operate your vehicle—even at 0.05% or 0.06%—you may still be arrested and charged under the state’s DWI statute.
New Hampshire law focuses on whether “a person is under the influence of intoxicating liquor or any controlled substance” to a degree that impairs their ability to drive—not solely on their BAC level.
Signs of Impairment That Can Lead to Charges
In practice, police officers in New Hampshire are trained to assess a wide range of factors beyond BAC when evaluating whether a driver is impaired. If your BAC is under the legal limit but you show noticeable signs of impairment, you can still face a DWI charge.
Here are some of the indicators officers may use to justify arrest and charges:
- Erratic driving behavior: Swerving, drifting, inconsistent speed, or difficulty staying in a lane
- Slow reaction time: Delayed responses at stop signs or traffic lights
- Physical symptoms: Slurred speech, red or glassy eyes, lack of coordination
- Performance on field sobriety tests: Inability to walk a straight line, balance on one leg, or follow instructions
- Driver admission: Statements like “I only had a couple of drinks” may be used as context for evaluating impairment
These observations become especially important if the driver’s BAC is under 0.08%. In that case, the officer must show that alcohol or another substance still caused functional impairment while operating the vehicle.
Legal Basis in New Hampshire for DWI Below 0.08%
New Hampshire’s impaired driving statute does not require a BAC of 0.08% or higher to charge a driver with DWI. The law states that a person can be guilty of DWI if they are operating a vehicle:
“While under the influence of intoxicating liquor or any controlled drug, prescription drug, over-the-counter drug, or any other chemical substance, natural or synthetic, which impairs the ability to drive.”
This language gives law enforcement and prosecutors the legal foundation to pursue DWI charges regardless of BAC, as long as they can demonstrate impairment.
For example:
- A BAC of 0.06% combined with poor driving behavior and failed field sobriety tests could result in a conviction.
- A BAC of 0.04% in a driver operating a commercial vehicle may be enough to exceed the legal limit for that category.
- A driver under 21 years old with a BAC of 0.02% or higher is already over the limit for their age group under New Hampshire’s zero-tolerance policy.
This flexibility in enforcement ensures that the law covers a wide range of potentially dangerous situations—particularly in cases where alcohol affects individuals differently.
Medications, Drugs, and Combined Effects
It’s also worth noting that DWI charges in New Hampshire aren’t limited to alcohol. Drivers can be charged if any substance—including legal medications—impairs their ability to operate a vehicle safely.
For instance:
- Prescription drugs: Certain medications for anxiety, pain, or sleep may cause drowsiness or delayed reactions.
- Over-the-counter remedies: Even cold medicines containing alcohol or sedatives can impair driving ability.
- Combination of alcohol and medication: Even if your BAC is low, combining alcohol with another impairing substance may cause enough impairment to justify a DWI arrest.
In such cases, even a BAC well below 0.08% may still result in a charge if combined with other substances that impact driving.
Real-World Scenarios Where DWI Charges Happen Below the Limit
To better understand how this works in everyday life, here are a few realistic examples of how someone could be charged with DWI in New Hampshire below the 0.08% threshold:
Scenario 1: The Social Drinker
A person attends a dinner and has two glasses of wine. Their BAC is measured at 0.05%. On the drive home, they run a stop sign and swerve slightly while adjusting the radio. An officer pulls them over, notices the odor of alcohol, and administers field sobriety tests, which the driver fails. Result: DWI charge.
Scenario 2: The Medication Mix
A driver takes prescription medication for anxiety, which includes a warning against operating heavy machinery. Later, they have one alcoholic drink and drive to a store. Their BAC is 0.03%, but they appear disoriented and are weaving between lanes. Result: DWI charge due to combined effects of alcohol and medication.
Scenario 3: The Underage Driver
A 19-year-old drinks one beer at a party, then drives. Their BAC is 0.02%—the legal limit for drivers under 21. Even though their driving is not erratic, a traffic stop reveals the alcohol consumption. Result: DWI charge under the state’s zero-tolerance policy.
These examples show that the legal limit is not a guarantee of legal safety—and that impairment can lead to charges even when BAC is technically “under the limit.”
How BAC Is Only One Part of the Equation
In short, BAC is a helpful metric for law enforcement, but it’s not the only factor used to assess impairment. New Hampshire’s DWI laws are designed to be broad and flexible, allowing officers and courts to use a range of evidence to evaluate whether someone was unfit to drive.
Important takeaways for drivers:
- BAC levels don’t reflect how alcohol affects everyone equally. A BAC of 0.06% might have little impact on one person and serious effects on another.
- Performance during traffic stops—speech, balance, coordination—can outweigh a “low” BAC.
- Drivers are responsible for their condition behind the wheel, regardless of chemical readings.
Understanding that a charge can occur below 0.08% helps clarify why driving after any alcohol consumption—especially when mixed with medication or fatigue—can be legally risky.
Frequently Asked Questions (FAQ)
Can I get a DWI in New Hampshire if my BAC is below 0.08%?
Yes. If law enforcement believes you’re impaired, you can still be charged even with a BAC below the legal limit.
Is BAC the only factor used in a DWI arrest?
No. Officers consider physical behavior, driving patterns, speech, and performance on field sobriety tests.
What if I’m under 21 and my BAC is 0.02%?
That’s the legal limit for underage drivers in New Hampshire. You may be charged even if your BAC is well below 0.08%.
What if I was taking prescription medication and had a small amount of alcohol?
Combining medication with alcohol may lead to impairment—even at low BAC levels—and can result in a DWI charge.
Does everyone have the same tolerance at the same BAC?
No. Factors like body weight, gender, food intake, and metabolism influence how alcohol affects each person.
How can I avoid this situation?
The only sure way to avoid DWI charges is not to drive after consuming any alcohol or impairing substance.
Conclusion
In New Hampshire, you can absolutely be charged with a DWI even if your BAC is below the legal limit of 0.08%. The law allows officers and courts to evaluate impairment based on the totality of the circumstances—not just a number. From driving behavior and field sobriety tests to medication use and age-related thresholds, many factors influence whether a DWI charge is appropriate.
To understand more about how BAC is measured and interpreted in DUI laws, visit the Blood Alcohol Content And Legal Limits pillar page.
For an in-depth explanation of what BAC means under DUI laws, explore our What Blood Alcohol Content (BAC) Means Under DUI Laws mini-hub article.