DUI DEFENSES: How Accurate Are Breathalyzers?

HOW YOUR LOS ANGELES DUI DEFENSE ATTORNEY CAN CHALLENGE THE ACCURACY OF BREATH TEST DEVICES
Many people simply assume that breathalyzers are an accurate tool used by law enforcement personnel to judge whether a driver is intoxicated.  In California (and every other US state), the legal limit for blood alcohol concentration (BAC) is .08.  When attempting to ascertain how much alcohol in a driver's blood, the most accurate measure is to have a sample of the driver's blood.  Why then, do people assume that breath can tell us, accurately, how much alcohol is in someone's blood?  Why do police officers and courts use these inaccurate blood results?  The answer:  Well, Thomas Jefferson just might roll all the way out of his grave and write a new Declaration of Independence if police were taking blood from drivers based on mere suspicion, or worse, at DUI checkpoints.  This is what criminal defense attorneys are fighting every day.

Understanding how a breathalyzer estimates BAC is fundamental to understanding why they are inherently inaccurate.  It should be obvious that a breathalyzer does not ever actually measure blood.  Breathalyzers may give a fairly accurate indicator of "breath alcohol" but that measure has no legal value and does not accurately indicate alcohol impairment.  To convert a breath alcohol finding into a blood alcohol finding, breathalyzers multiply the amount of alcohol in the breath by 2100.  The manufacturers of these devices have concluded that the average concentration of alcohol in someone's blood will be 2100 times the concentration of alcohol in the breath.  This method is inherently flawed.  This number is known as partition ratio, and can range in actual people from as low as 1100 to as high as 3200.  Even if the tests are performed without human error, the presence of mouth alcohol is not affecting the tests and the machine has been properly calibrated, breath alcohol does not equal blood alcohol (nor is it consistently proportional).  A person could be found guilty of DUI, simply for being different than the "average" person.

Imagine you have five jars of loose change.  In each jar, a random assortment of pennies, nickels, dimes, quarters, and the occasional Canadian coin that found its way into the mix.  You count one of the jars and find that it contains $21.43.  Instead of counting all of the change, you multiply by five and fill out a deposit slip for $107.15 and take it to your bank.  What reaction would you expect from the teller?  What if the jar you counted was heavy in pennies?  What if it had more dimes?  What if instead of five jars, you had 2100 jars?  What if you guessed how many jars you have?

Breath tests have begun to to show their true colors.  More and more, people charged with DUI based on a breath test are taking their cases to trial, and expert witnesses are testifying that the method fails to prove BAC beyond a reasonable doubt.  Just how far off breathalyzers are depends on your source, but scientific studies have found margins of error ranging from 15 to 50%. 

If your bank wouldn't accept a mere estimate of how much loose change you're depositing into your account, how can a court of law accept a BAC estimate as evidence of guilt beyond a reasonable doubt?

If you've been charged with DUI, you need a Los Angeles DUI Attorney to help you assert the defenses that apply to your case.  Inaccurate machines shouldn't cost you your liberty or driving privilege.  Contact our office for a free consultation.

IMPORTANT LINKS:
LA Sheriff's Inmate Locator 
Los Angeles Superior Court  
Los Angeles Police Department
Los Angeles Felony Bail Schedule
Los Angeles Misdemeanor Bail Schedule

Nicholas M. Loncar, Esq. 
Los Angeles Criminal Defense Attorney
t: 213-375-3775 | f: 213-375-3099
Mobile: 323-803-4352 
[email protected]
1200 Wilshire Blvd | Suite 406
Los Angeles, CA | 90017
www.iDefendLosAngeles.com

By Nicholas Loncar

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