The Top Five Things You Should Know About Breathalyzers and Blood Alcohol Content (BAC)


If you've never been stopped on suspicion of DUI, you will likely be unfamiliar with the specifics behind breathalyzers and blood alcohol content (BAC).

While you'll likely know what a breathalyzer test is and maybe even that it's illegal to drive with a blood alcohol content of 0.08% in all 50 states, you may not know how a breathalyzer works and what test results may mean in a case.

This lack of knowledge could be a good thing because it probably shows that you've never been pulled over on suspicion of drunk driving. Vice versa, this lack of knowledge could be bad if you ever have to submit to a breathalyzer since these test results are now the most common and powerful form of evidence in most DUI cases.

Whether you're facing DUI charges or just want to learn more about the testing process, you'll find this list below to be an important source of information to help educate yourself on drunk driving.

And for even more guidance on breathalyzers, the DUI laws in your state and other DUI information, be sure to speak with a DUI attorney in your area.

1) A Breathalyzer Is An ESTIMATION and NOT A READING of Your BAC!

Many people think that breathalyzers read your blood alcohol content when in fact, they actually estimate your BAC levels.

A breathalyzer attempts to convert your breath alcohol content to BAC by measuring blood alcohol in your breath from the lungs. While a reading suggests more validity, an estimation is what it is: an educated guess.

2) Breathalyzer Calculations May Make FALSE Assumptions about You!

Since breathalyzers estimate BAC, their results may be open to interpretation. This fact is especially evident when understanding how breathalyzers convert breath alcohol content to blood alcohol content.

In order to make this conversion, breathalyzers assume a standard ratio of 2100:1 between BAC and breath alcohol content. This ratio assumes that the man or woman being tested is an "average person" in terms of weight, health and other factors relating to his or her age group.

It has been shown that this ratio can vary anywhere from 1700:1 to 2400:1 within individuals. In other words, a breath test result of 0.08% may actually vary from 0.65% (under the legal limit) to 0.09% (above the legal limit); further demonstrating how breathalyzers are far from perfect.

3) You May STILL BE CONVICTED of DUI Despite a Legal BAC Test Result!

Assuming that the breathalyzer made an accurate estimation of BAC, some people may be of the opinion that they can not be convicted of DUI if the breath test result is below 0.08%.

This is not always true. You may still be charged and later convicted of DUI if you fail field sobriety tests in spite of your breath test result.

And if you're under the age of 21, merely having any alcohol on your breath may be enough for a DUI charge and conviction. All 50 states have strict zero tolerance policies which make it illegal for underage drinkers to operate a motor vehicle with a BAC at 0.02 or even lower.

4) Just ONE OR TWO Drinks Could Result in an Illegal BAC!

Many people may think that they can have a few drinks and still be able to legally drive. This notion is not always true as BAC can vary within people based on many factors. For example, if you are below the average weight of your age group and haven't eaten all day, a couple of drinks may be enough to push you to 0.08%.

And there's always the issue of what constitutes a drink. As the Paris Hilton DUI arrest revealed, one drink may actually be equivalent to two or more drinks.

Here are just a couple of good examples: One Long Island Iced Tea is equivalent to five drinks while one Pina Colada is really three drinks.

5) Know the DUI Laws in your State BEFORE REFUSING A BREATHALYZER!

If you've never been stopped on suspicion of DUI, you may wonder if you should agree to a breathalyzer test. While you may refuse a breathalyzer test, you should be aware of the DUI laws in your state before making such a decision.

Many states are beefing up penalties for breathalyzer refusals, and the risk may not outweigh these additional costs in your situation. Educate yourself about the laws in your state!

If you're interested in talking with a local DUI attorney to learn the specific breathalyzer laws in your state, fill out the free case evaluation form below.

Free Case Evaluation

» Back to DUI Articles

Copyright © 2018 MH Sub I, LLC. All rights reserved. ® Self-help services may not be permitted in all states. The information provided on this site is not legal advice, does not constitute a lawyer referral service, and no attorney-client or confidential relationship is or will be formed by use of the site. The attorney listings on this site are paid attorney advertising. In some states, the information on this website may be considered a lawyer referral service. Please reference the Terms of Use and the Supplemental Terms for specific information related to your state. Your use of this website constitutes acceptance of the "Terms & Conditions", "Supplemental Terms", "Privacy Policy" and "Cookie Policy."