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How a Breathalyzer Works

Just by driving on a road in Virginia, you are giving your implied consent to submit to a breath or blood test for alcohol content if you are pulled over. Law enforcement officers utilize breathalyzers to determine whether you are driving under the influence.

In Virginia, it is illegal to operate a motor vehicle while having a blood alcohol concentration (BAC) of 0.08 percent or greater. For persons under the age of 21, the maximum BAC is 0.02 percent. A Leesburg drunk driving lawyer can provide legal guidance on penalties associated with these BACs for those in the Northern Virginia area.

But just how does a breathalyzer figure out how much you have had to drink?

What a breathalyzer does

A breathalyzer is a device featuring:

  • A breath sampling system
  • Two glass vials to create a chemical reaction
  • A meter to measure the change in color caused by the chemical reaction

In order to measure alcohol, a suspect breathes into the device. The sample of breath is bubbled in one vial through a mixture of potassium dichromate, sulfuric acid, water and silver nitrate. At this point, the sulfuric acid removed the alcohol from the air. Then the alcohol reacts with potassium dichromate.

During this reaction, the reddish-orange dichromate ion changes color to green chromium ion when it reacts with the alcohol. The mixture is compared to an unreacted mixture, producing an electric current that causes the needle in the meter to move. The law enforcement officer then turns a knob on the meter to read the level of alcohol in the reacted mixture. This determines your blood alcohol content.

Breathalyzer problems

Like most machines, breathalyzers are not perfect. Some of the common usage problems include:

  • Misreadings with people using asthma inhalers
  • Misreadings due to mouthwash, which can contain as much as 25 percent alcohol
  • Reliance on an algorithm to determine blood alcohol content
  • Miscalibration of the breathalyzer system
  • Low-carb diets producing ketone bodies, which can be misread as blood alcohol content by a breathalyzer
  • Medical conditions that mimic impairment

Defense against breathalyzers

Being arrested for driving under the influence (DUI) based on a breathalyzer test may seem hopeless. But a skilled attorney can give you hope. An attorney can look at how a breathalyzer was used, determine whether it was used correctly and uncover other factors that could have affected the reading.

Our Leesburg law firm has successfully defended DUI suspects against inaccurate or improperly administered breathalyzer and field sobriety tests. We use our knowledge of questionable readings to mitigate the case and reduce the penalties involved in a DUI. If you are arrested for a DUI in Leesburg, contact Simms Showers LLP.

Contact an experienced attorney today

Simms Showers LLP represents clients throughout Northern Virginia, including Leesburg, Sterling and the surrounding areas of Loudoun County as well as Arlington County, Clarke County, Frederick County, Fairfax County and Prince William County.

Simms Showers LLP
305 Harrison Street SE, Third Floor
Leesburg, Virginia, 20175 USA