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Everything You Need to Know About Blood Alcohol Concentration (“BAC”)

by | Apr 29, 2021

What is BAC?

A person’s blood alcohol concentration is commonly referred to as the acronym “BAC”. Blood alcohol concentration is defined as the percentage of alcohol in a person’s bloodstream. It is critical for a drunk driving defense lawyer to understand the intricacies of BAC calculations and testing.

What factors affect my BAC?

A myriad of factors affects your BAC level. Several of these factors include:

  • How quickly did you drink? The faster that you drink, the quicker your body will reach peak BAC and the more quickly you will become intoxicated.
  • How much do you weight? On average men have more blood in which to dilute alcohol due to their greater size. However, in a scenario involving a man and woman of equal size the man still has slightly more blood to dilute the alcohol. This is because men generally have more muscle tissue than women and muscle contain more water than fat.
  • What did you last eat? Roughly 20% of alcohol is absorbed into your bloodstream through your stomach. If your stomach is full the alcohol is absorbed more slowly into the bloodstream. This is because a full stomach prevents the food from moving to your small intestine where the remaining 80% of the absorption takes place. Fatty foods take longer to digest and therefore take longer to move to the small intestine. Therefore, fatty foods are the most efficient at slowing alcohol absorption.
  • Did you use a mixer? Carbonated beverages speed up the absorption process of alcohol. Water and fruit juices have the opposite effect on alcohol absorption.
  • Are you taking any medications? Many medications have a synergistic effect on your blood alcohol concentration. A synergistic effect means that the medications amplify the effects of the alcohol. Such medications include aspirin, anti-depressants and cough medicines.
  • What’s your biological gender? As this video from BACtrack.com demonstrates, gender has an important role in calculating BAC.

If arrested for drunk driving, an experienced drunk driving defense Attorney Dan Skarie will analyze these factors to judge the reliability of your reported BAC result.

How quickly will my BAC go down?

Alcohol is a toxin that your body must neutralize or eliminate. First, the body will eliminate ten percent through sweat, breath and urine. Second, the liver, will detoxify the remaining alcohol. Your liver produces the enzyme alcohol dehydrogenase which breaks down alcohol into ketones. The breakdown of ketones occurs at approximately .015 g/100ml/hour. Put in other words, your BAC level will reduce on average .015 per hour. This is approximately one standard drink per hour.

Are there any tricks to sober up faster?

As stated, once the alcohol is in your blood stream it can only be eliminated by enzymes in your liver or sweat, urine and breath. Techniques such as sleep, water, coffee, energy drinks or a cold showing will not increase the process. The techniques may minimize symptoms but do not reduce your BAC level.

Can I calculate my BAC Level?

You can calculate an estimate of your blood alcohol concentration. The three main variables are gender, number of standard drinks and hours passed. The Chemical Test Section of the Wisconsin State Patrol created a handy chart for calculating your BAC.

There are also a variety of smart phone applications that purport to calculate BAC using a similar formula. Here is a link to Alcohol.org’s BAC calculator: https://www.alcohol.org/bac-calculator/.

What is a standard drink in calculating BAC?

Blood alcohol concentrations are calculated using standard drinks. A standard drink is defined as:

  • 12 ounces of beer, or one bottle at 5% alcohol
  • 8 ounces of malt liquor at 7% alcohol
  • 5 ounces of wine at 12% alcohol
  • 1.5 ounces of hard liquor, or one shot, at 40% alcohol.

What are the expected symptoms at a specific alcohol level?

There have been thousands of studies on the effects of alcohol. The following is a simple chart from the University of Notre Dame outlining the expected symptoms for the average drinker at a particular BAC range.[4]

  • 0.020-0.039%: No loss of coordination, slight euphoria, and loss of shyness. Relaxation, but depressant effects are not apparent.
  • 0.040-0.059%: Feeling of well-being, relaxation, lower inhibitions, and sensation of warmth. Euphoria. Some minor impairment of judgment and memory, lowering of caution.
  • 0.06-0.099%: Slight impairment of balance, speech, vision, reaction time, and hearing. Euphoria. Reduced judgment and self-control. Impaired reasoning and memory.
  • 0.100-0.129%: Significant impairment of motor coordination and loss of good judgment. Speech may be slurred; balance, peripheral vision, reaction time, and hearing will be impaired.
  • 0.130-0.159%: Gross motor impairment and lack of physical control. Blurred vision and major loss of balance. Euphoria is reducing and beginning dysphoria (a state of feeling unwell)
  • 0.160-0.199%: Dysphoria predominates, nausea may appear. The drinker has the appearance of a sloppy drunk.
  • 0.200-0.249%: Needs assistance in walking; total mental confusion. Dysphoria with nausea and vomiting; possible blackout.
  • 0.250-0.399%: Alcohol poisoning. Loss of consciousness.
  • 0.40% +: Onset of coma, possible death due to respiratory arrest.

What is the blood alcohol concentration limit in Wisconsin?

The legal limit in Wisconsin is .08 g/100mL of blood. If you provide a blood test sample to law enforcement, the reported result of the sample is your alleged BAC at the time of test. Important, for purposes of your case, is that this number is not reflective of your BAC at the time of operation. An experienced drunk driving defense attorney will assist you in determining your BAC at the time of driving. Such knowledge could mean the difference between a guilty and not guilty verdict.

When you need a defense attorney.

If you have the unfortunate situation of needing a DUI or DWI lawyer, we are here to help. Mistakes happen. Despite being in the wrong, you still have rights and need representation. Give us a call to schedule a consultation and walk you through the process you will be going through.

About the Author:

Attorney Daniel R. Skarie is a tenacious drunk driving and criminal defense attorney practicing throughout Wisconsin. Contact Attorney Skarie at his website, or connect on Twitter or LinkedIn.

Written by Vanden Heuvel & Dineen, S.C.

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