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Can I drive if a pocket breathalyzer shows I'm below the limit?

​Responsible drivers may try and use a pocket breathalyzer to test their blood-alcohol level before deciding whether or not to drive home. This can be a good tool to get an estimate of the driver's blood alcohol content (BAC) but it should not be relied upon to determine if the driver is impaired or over the legal limit.

Pocket breathalyzers can be unreliable and a faulty test could give drivers the false confidence to drive home while impaired. If a driver is pulled over on suspicion of a DUI, the police officer may not care that a portable breath test showed a below-the-limit result. If you or a loved one is arrested for a DUI in the East Bay, contact the experienced California DUI lawyer Lynn Gorelick today.

Are portable breath testing devices reliable?

Pocket breath testing devices, or “breathalyzers,” can be very inaccurate. It is really difficult to know when the breathalyzer is giving an accurate result or false measurement. The problems with the device may have to do with the machine itself, battery, or person taking the test. Issues may include:

  • Improper calibration,
  • Design or manufacturing defects,
  • Not cleaning the device,
  • Taking the test right after consuming alcohol,
  • Mouthwash or other foods affecting the test, or
  • Operator error.

How can my BAC increase after I took a breath test?

A person's blood-alcohol level changes over time. Just as the effects of alcohol take time to wear off, it takes time for alcohol to be absorbed by the body and go to the bloodstream. A number of factors can impact the time frame of alcohol's effects, including food, weight, and even dehydration.

If you take a pocket breath test shortly after drinking a few shots of alcohol, the results may show the breath showed a below-the-limit BAC. After waiting for the alcohol to be absorbed into the body, the breathalyzer may show an over-the-limit BAC. The breath testing results can change over time as alcohol is absorbed and processed by the body. A breath test only gives a snapshot of the individual's breath alcohol level at that moment.  

Why can the police use a portable breath testing device?

When the police suspect a driver is impaired by alcohol, they may ask the driver to submit a breath test using a preliminary alcohol screening (PAS) test. This PAS test, sometimes called a breathalyzer, is a roadside test using a handheld device. It is important to understand the difference between a PAS device and the breath testing machines the police use at the jail or police station.

PAS Breath Tests

The PAS is generally used for gathering evidence in the field. The police may use this device to support the probable cause needed to make an arrest. However, the results of the PAS may not admissible in evidence of the driver's BAC number during trial.

The PAS test results are not always accurate, which is one reason why they may not be used as evidence of the driver's BAC level. The testing conditions of a roadside test are also not as stable and there are a number of things that could give a false or incorrect result.

Roadside PAS tests are also not required. A driver can refuse to give a PAS test sample and there are no penalties for refusing a roadside breath test. However, if you are currently on DUI probation or under 21, refusal to take a PAS can result in a driver's license suspension. 

Breath Testing After Arrest

After a driver is arrested, he or she will be asked to submit a breath or blood sample for testing. These tests are generally used as evidence of the driver's alcohol level. To ensure they are more accurate, the police also have to follow certain procedures, including observing the individual for a certain amount of time before the test.

Chemical tests are also required under California's “implied consent” laws. Refusing a chemical test after a DUI arrest can result in a license suspension for a year or more, even if the driver was totally sober.

DUI Defense by East Bay Criminal Defense Lawyer

East Bay attorney Lynn Gorelick has more than 30 years of DUI experience and understands how unreliable breath testing devices can be. Pocket breathalyzers, PAS devices, and even more complex breath testing machines can all have problems that can give a false alcohol reading. If you are facing criminal charges for a DUI in Contra Costa County and Alameda County, contact East Bay DUI lawyer Lynn Gorelick today.

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