If you’ve been pulled over for Driving While Impaired in North Carolina, the first thing that the officer must do is determine your level of intoxication. This is typically done by conducting field sobriety tests and administering a breath test. Whether you had one drink or several, it’s important to understand that there are many factors that can impact BAC — and these factors can sometimes be used to form a strategic defense in a DWI case.

What is BAC?

Blood Alcohol Concentration (commonly referred to as “blood alcohol content” or simply by the acronym “BAC”) is the percentage of alcohol in a person’s bloodstream. When alcohol enters the body, it goes through the stomach and the small intestine. Then, it goes into the bloodstream where it will stay until it is filtered out by the liver. Whatever amount of alcohol is left that cannot be metabolized by the liver continues to circulate in the bloodstream.

While breath tests are the most common method of determining BAC, blood and urine tests can also measure the amount of alcohol in a person’s bloodstream. In North Carolina, the legal BAC limit is .08%. It is illegal for a driver to operate a vehicle with a BAC of this percentage or higher. For commercial vehicle drivers, the limit is .04%. There is a zero-tolerance policy for drivers under the age of 21 with any amount of alcohol in their system.

What Impacts a Person’s BAC?

Generally, a person’s liver can process approximately one standard drink containing 0.6 ounces of alcohol every hour. However, there can be many other variables that impact BAC level, including weight, genetics, type of alcohol consumed, and pattern of drinking. Despite many myths purporting the contrary, nothing can lower BAC level except time — a person’s BAC typically drops .015% every hour they do not consume alcohol.

Additional factors that affect BAC can include the following:

• The rate of consumption — How fast you drink has a direct impact on your BAC level. Your BAC will typically be higher after consuming two alcoholic beverages in one hour than if you drank them over a two-hour period.
• Food in your stomach — Your BAC level will rise faster on an empty stomach than when there is food in it. Eating before or while drinking can slow the rate at which a person’s body absorbs the alcohol into the bloodstream.
• Your gender — Since they have less water in their bodies than men, a woman will usually reach a higher BAC level after consuming the same amount of alcohol as a man. Men and women also differ in body size and composition which causes each drink to be more concentrated in a woman’s bloodstream.
• Fatigue and stress levels — Alcohol can affect a person more if they are tired or stressed. Since alcohol is a depressant, it can increase the effects of fatigue or stress.
• Medications you’re taking — Certain medications can result in a false positive on a breathalyzer test. For example, over-the-counter medications such as Nyquil, Vicks products, and certain cold medications contain alcohol as an ingredient and can cause a higher BAC result. Some mouthwashes also have a high content of alcohol and can affect breathalyzer results.
• Medical conditions — Certain types of medical conditions can skew the results on a breathalyzer, regardless of how much (or even if any) alcohol was consumed. For instance, people who suffer from diabetes, acid reflux, and other gastro disorders may register higher BAC levels.

Any of the above factors that affect BAC can cause a false positive on a breathalyzer test or show results that might be higher than what your BAC actually was at the time you were pulled over. In some DWI cases, BAC results can be challenged if the breathalyzer machine was not calibrated correctly or maintained properly. You might also be able to assert a defense if the officer was not trained in how to administer the breathalyzer or an unreasonable amount of time lapsed between the arrest and when you were given the test.

Does Tolerance Affect BAC?

Critically, alcohol tolerance and BAC should not be confused. Alcohol tolerance can vary significantly from person to person. However, someone’s tolerance for alcohol won’t change their BAC level — it simply means they will not feel that intoxicated, even if their BAC is above the limit. In other words, having a high tolerance for alcohol will make that person feel less affected by it and it would take more alcohol for them to reach the same physiological response as someone with lower tolerance.

Contact an Experienced North Carolina DWI Criminal Defense Attorney

If you were arrested for a DWI, it’s essential to have a skillful criminal defense attorney by your side to protect your rights. The Johnston County DWI defense attorneys at Reece & Reece, Attorneys at Law provide aggressive advocacy for a broad scope of criminal and traffic-related offenses, including DWI charges. Call (919) 300-1249 to schedule a consultation and learn how we can help.