Breathalyzer vs. Blood Alcohol Content (BAC): An Important Difference & Why It Matters to You!
While you've likely heard of a breathalyzer before, you may be unaware of what it actually does, especially if you've never been pulled over on suspicion of DUI!
Many people speak of "breathalyzer" and "blood alcohol content" (BAC) as the same thing when there is a very important difference. A breathalyzer does not read your BAC, but rather estimates it.
So what does this mean? This means that breathalyzer test results are far from 100% certain and may often be challenged.
In the following sections, learn:
- Why BAC Does Matter?;
- How Law Enforcement Measures BAC?;
- What Are Some Problems with Breathalyzer Tests?; and
- What This Means for You?
Why Does BAC Matter?
Blood alcohol content is important because it is illegal in all 50 states to drive or otherwise operate a motor vehicle with a BAC of 0.08 percent or greater. If you have a BAC of 0.08 or higher, you may possibly be convicted of DUI even if you passed field sobriety tests or did not appear impaired. Following conviction, you may be subject to a variety of DUI penalties like license suspension, probation or even jail time with the possibility of a prison term.
How Does Law Enforcement Measure BAC?
Your BAC may be tested several ways. The breath test is the most common way to estimate BAC. Many police departments use portable breathalyzer testing devices to try to determine BAC. Some states do not allow test results from these portable breathalyzers and rather use larger machines which are generally considered more accurate. A urine test may also be used to estimate BAC.
While many states rely solely on breath or urine tests to estimate BAC, a blood test is the most reliable way to get an accurate result!
What Are Some Problems with Breathalyzer Tests?
Several problems exist with breathalyzers that could result in an inaccurate estimation!
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Did you know that breathalyzers assume a specific ratio between BAC and breath alcohol content in order to make their estimations? This 2100:1 ratio may actually range between 1700:1 and 2400:1; a variation which could mean all the difference in your case.
How so? Let's say the breathalyzer test estimates your BAC at 0.08 percent. In this case, your BAC may really vary between 0.065 percent (legal) and 0.09 percent (illegal). If you had a BAC 0.065 percent (legal), a showing of impairment would be required.
Urine tests also make estimations based on an assumed ratio (1.3:1) which may not apply for every person.
- Breathalyzer machines are often confused by other substances which throw off BAC estimations. A breathalyzer machine tests for ethyl alcohol (ethanol) from alcoholic substances, and may misread many other substances in the human breath as alcohol content. Here are some interesting examples.
- Some breathalyzer machines become confused by acetone, which may be present in large amounts in diabetics and other people with special diets.
- Breathalyzers have also been confused by fumes coming from certain paints, adhesives and paints. In one dramatic example, a painter who was exposed to similar fumes but did not have any alcohol in his system registered a 0.075 BAC. His true BAC was later determined to be 0.00.
- BAC levels may be impacted by physical activity. One study found that running up and down the stairs right before a breath test could decrease BAC by up to 25%.
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What Does This Mean to You?
If you've been charged with a DUI based on a breathalyzer or urine test, a DUI lawyer may be able to help you challenge those results. Fill out our free case evaluation form or call 1 (877) 349-1311, and we'll help you schedule a free consultation with a local DUI attorney who can begin looking at your charges.