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How Reliable are Breathalyzers?

Posted by Christopher Martens | Jul 10, 2015 | 0 Comments

If you are pulled over on suspicion of a DUI, the officer who pulls you over will ask you some questions, look for signs that you have been drinking and may give you a series of tests. To gather evidence you have been driving under the influence, you may be given a field sobriety test and/or given a breathalyzer test. Contrary to what some may think, you have the right to politely decline taking a breathalyzer test if asked by an officer when pulled over. However, if you are arrested, they are no longer asking you to take a breathalyzer test, they are requiring you. California's implied consent law mandates that California drivers submit to a breathalyzer or blood test at the point of arrest to measure your blood alcohol concentration at the time you were driving. In applying for your California driver's license, you implicitly agreed to consent to one of these tests, which is why it is called implied consent. You do not necessarily have to verbally consent to the test at the time of arrest, because you in effect already did so when you applied for your driver's license. Unfortunately, breathalyzer tests are notorious for being inaccurate for a variety of reasons. California DUI laws are based on your blood alcohol concentration, or BAC, not you breath alcohol concentration. However, the breathalyzer test does not directly measure your BAC at all. It essentially estimates your BAC by measuring the amount of alcohol in your breath. That being said, it isn't the most reliable test in terms of accurately measuring your BAC. You do have the right to decline the breathalyzer test and take a blood test instead. Your arresting officer should review this option with you; it is fine to defer the breathalyzer in favor of a blood test, so long as you are cooperative. In lieu of a blood test, certain individuals will be able to take a urine test instead, however these are widely considered unreliable as well. Urine tests only measure the metabolites of alcohol in your urine, meaning they indirectly estimate your BAC, much like a breathalyzer does. However, the presence of alcohol metabolites in your urine is not necessarily an indicator of recent alcohol consumption; everyone processes alcohol at varying rates and urinates at different frequencies. Due to this unreliability, urine tests are also only available when a breath or blood test is unavailable. Breathalyzer tests are certainly more inaccurate than blood tests but are less invasive. Similarly, because they are notoriously unreliable, the BAC test results they produce for a DUI conviction are often challenged, and sometimes successfully. Breathalyzers are just machines with small computers in them. As we all know, computers sometimes don't work, especially when not properly maintained or looked after. Breathalyzers need regular calibration and maintenance to achieve an appropriate, and legally permissible, level of accuracy. California police departments have standard procedures for the calibration, maintenance and use of breathalyzers, which includes keeping records of all work on the machine and all authorized users, thus making it easy to confirm whether or not the machine was in good working order at the time it was used on the defendant. If the accuracy or reliability of the breathalyzer is successfully challenged in court, the BAC reading it produced as evidence for the case will be ruled inadmissible. To know when a breathalyzer BAC reading may be inaccurate, it is a good idea to get to know how your body processes alcohol. There are online calculators that can estimate what your BAC might be, based off of the type of drink you had, by alcohol percentage, how much you drank, how fast you drank it and your weight. These are just estimates as well. Measuring blood alcohol concentration is difficult; short of a blood test, all results will be estimated to some extent. If properly maintained and calibrated, however, breathalyzer tests can produce fairly accurate results. If you are facing DUI charges and feel the results from your breathalyzer test seem inaccurate or doubt the breathalyzer was properly calibrated and maintained, contact an experienced DUI defense attorney right away. A skilled attorney will be able to evaluate your case facts and advise you on how to best challenge the evidence against you. DUI convictions come with serious consequences that will last for years to come; don't let yourself be convicted over inaccurate breathalyzer test results.

If you or a loved one is facing DUI charges in the Tulare, Kings or Fresno County area, contact experienced DUI defense attorney Christopher Martens for expert counsel. The skilled legal team at The Law Offices of Christopher Martens can help you build a defense, which may include challenging inaccurate breathalyzer results. Contact our offices in Hanford and Visalia at 559-967-7386 or email us at [email protected] to discuss your case.

About the Author

Christopher Martens

Bio Visalia and Bakersfield criminal defense attorney who has dedicated his life to helping those who have been accused of crimes or injured due to the negligence of others.


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