What Is Blood Alcohol Concentration?

If you’re familiar with Texas’ DUI laws, you may be aware that a person is legally considered intoxicated if they have a blood alcohol concentration (BAC) of .08% or higher. But you might not know what a BAC actually is or how it’s measured. We’ll cover that in this blog.

What Happens When You Drink Alcohol?

Let’s say you’re out with your friends having a couple of alcoholic beverages. When you swallow the substance, it flows down to your stomach. Most of the alcohol is taken to the liver to be digested.

The liver can only process certain amounts of alcohol at a time, and the leftovers are absorbed by your stomach and taken into your blood. Some of the alcohol-infused blood passes through the alveoli, which are air sacs in your lungs. When this happens, your breath contains traces of alcohol.

What Does the BAC Represent?

Your BAC is a ratio of alcohol to blood in your body. For instance, if a breath test reveals that you have a BAC of .10%, that means you have one part alcohol for every 1,000 parts blood.

Typically, your blood alcohol concentration indicates how drunk you are. For instance, if you have a BAC between .01% and .03%, you might not have any noticeable effects. However, as your BAC rises, the effects of alcohol might become more apparent. With a BAC between .07% and .09%, things such as your reaction time, coordination, vision, and speech might become impaired.

What Can Affect BAC Levels?

Technically, because the liver processes about 1 standard drink per hour, the more alcohol you have, the higher your BAC will be. A standard drink would be like having 1 12-ounce beer with 4.5% alcohol by volume. However, not everyone processes alcohol the same way, which means that what might impair your normal faculties wouldn’t necessarily affect someone else similarly.

Several factors can affect your BAC level, including:

  • Number of drinks
  • Length of time between each drink
  • How much you weigh
  • Your gender
  • If you’re taking medications
  • How much food you consumed recently

How Is Blood Alcohol Concentration Measured?

If you are pulled over on suspicion of driving under the influence, the law enforcement officer might conduct several different tests to determine your blood alcohol concentration.

Field Tests

While not exactly testing for the percent of alcohol in your body, field tests are used to determine whether it is impairing your ability to operate a vehicle safely. Because alcohol travels throughout your body, many of your basic functions could be impaired, such as vision, speech, and coordination. The field tests are employed to see if any of those are compromised.

During a field sobriety test, officers might look to see if your:

  • Speech is slurred
  • Focus is off
  • Body is swaying

Breath Tests

Breath tests can be conducted on the side of the road following a traffic stop or at the station after an arrest. These devices work by estimating how much alcohol is in your body (which hasn’t been broken down by the liver). The amount of alcohol you have in your breath correlates to how much is in your blood. The ratio is about 2,100 breath to 1 blood.

Blood Tests

In some situations, law enforcement might draw your blood to measure the amount of alcohol in your system. Although these tests require more resources than a breath test, they are often considered more effective because they directly measure BAC levels rather than using a ratio.

Urine Tests

Urine tests are considered the least accurate measure of BAC levels. Results are generated by dividing the amount of alcohol in the urine by a specific number, which is an average that can fluctuate between drivers. Additionally, because the bladder stores contents until it is emptied, your BAC could be recorded as higher than it actually was. Some experts don’t support urine tests that are conducted without a “first void,” which is when you first empty your bladder and then provide a testing sample the second time you urinate.

Schedule a Free Consultation with The Law Office of Rene A. Flores PLLC

Because various factors can affect your blood alcohol concentration, and measurement methods can produce inaccurate results, you could be charged with (and possibly convicted of) driving under the influence even though you weren’t intoxicated. Our forensic lawyer-scientist knows how testing tools work and how results can be flawed. When you hire us for your DWI/DUI case in Hidalgo County, we will fight to challenge the prosecution’s case against you.

To discuss your legal options during a free phone consultation, call us at (956) 606-3606 or contact us online.