Blood Alcohol Content (BAC) in DUI Cases

What Is Blood Alcohol Content (BAC)?

As a cornerstone of many DUI cases, it is important to recognize what BAC is exactly. Essentially, BAC refers to the amount of alcohol that is in a person's blood at any given moment; this is the most common scientific measure of a person's level of intoxication. When someone states that a defendant had BAC of 0.10 percent, it means that there were 0.10 grams of alcohol per 100 grams of blood.

BAC, however, will differ depending on the person. It can take different people different amounts of alcohol to reach the same BAC. Factors such as time spent drinking, type of alcohol, body weight and more can all play into BAC.

For example, if a 120 pound female drinks three glasses of wine in one hour, she will have an estimated BAC of 0.09 percent. If a 200 pound man drinks the same amount of wine over the same time frame, he may only have a BAC of 0.04 percent. This is just a hypothetical situation, but it does demonstrate how different factors can all affect differences in BAC.

Regardless of how much it takes to reach a certain BAC level though, once a person reaches it, certain effects may be experienced.

Effects of alcohol at different BAC levels is explained below:

• 0.010 – 0.029: Most individuals will appear normal.
• 0.020 – 0.059: Most individuals will be relaxed, happy and talkative. Some will have difficulty concentrating on tasks.
• 0.06 – 0.09: Most individuals will have decreased inhibitions and be more extroverted than normal. They may struggle with reasoning, as well as depth perception or their peripheral vision.
• 0.10 – 0.19: Most individuals will begin to over-express themselves and may experience violent mood swings. They may struggle with their reflexes and reaction times, resulting in staggering and slurring their speech. They may also have problems with their motor control.

Breath Test: An Unreliable Test of BAC

If you take a breath test, it does not directly measure the concentration of alcohol in your blood. Rather, it tests the concentration of alcohol in your breath and then by a calculation estimates blood alcohol concentration. As there are many variables that can contribute to the alcohol present in your breath, the test often gives an incorrect answer. Below are a number of questions that an experienced attorney may ask as they work to build a comprehensive defense on your behalf:

• Has the machine been recently calibrated?
• Did the officer tell you to keep blowing?
• Had you just finished drinking when you were stopped?
• Did you burp or belch during the testing process?
• Do you have a medical condition?
• Was the breath test machine adjusted for the temperature?
• Do you wear dentures, or have you recently had dental work?

Challenging the Breath & Blood Tests

You are required to take a breath test if told to do so by an officer, or you will lose driving privileges for a year – but what if the test you were commanded to take falsely accuses you of a DUI?

Breathalyzers can often be inaccurate. Most breath test machines use infrared spectroscopy to test the amount of methyl groups in your breath. These methyl groups are not only found in alcohol. They are a significant component in acetone: a common flammable liquid in gasoline, paint thinner, glue, and nail polish remover. If any of these substances are inhaled prior to a breath test, it can cause a test to read positive. Our own bodies produce a form of acetone as well as over 100 other methyl groups, which can also cause incorrect results.

Blood Tests for BAC

In the state of Florida, blood test administration is restricted to registered nurses and doctors or other "qualified persons." Police officers can conduct breath tests for BAC, but cannot perform a blood test for BAC.

Penalties for Refusing a Breath Test

Refusal to submit to a blood test results in one year of license suspension. Still, blood tests can be handled in ways that can cause your blood alcohol content to read positive when you are sober. Lack of sterilization, preservative or refrigeration issues, coagulation, and fermentation problems may cause an innocent person to be accused of drunk driving. As well, there is a possibility that your blood vial may have been mislabeled or switched, causing you to suffer the consequences for someone else's crime.