What is the Difference Between a Breathalyzer & Blood-Alcohol Content Test?
In the United States, it is illegal to operate a motor vehicle if you have a blood-alcohol content of 0.08 percent or higher. If you are stopped by police and the officers believe that you might be impaired, they may administer a field sobriety test. This is a sobriety test that is administered at the scene rather than at the police station. Field sobriety tests include walking in a straight line, reciting the alphabet backwards and blowing into a breathalyzer.
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Breathalyzers
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Breathalyzers are portable devices carried by police for use in the field. They work by detecting the amount of alcohol in a person's breath and use these results to gauge how much alcohol there is that person's blood. These can only produce accurate results if the assumed relationship between breath-alcohol content and blood-alcohol content is true of the person in question, which is often not the case.
Malfunctioning Breathalyzers
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Some breathalyzers give inaccurate results because they have confused ethyl alcohol with another substance. They are often thrown off by acetone, which is present in diabetics and in people on certain diets. It can also be thrown off by fumes from cleaning products and paint that may be present at the time of the test.
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Terminology
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While it is common for people to talk about breathalyzers and blood-alcohol content tests as if they were the same thing, they should not be used interchangeably. A breathalyzer test may be considered to be a blood-alcohol content test, but it is only an estimate that may produce inaccurate results. Urine tests are another type of blood-alcohol content test. The most reliable blood-alcohol content tests involve drawing blood. This may only be done at a police station. As a result, by the time a blood-based blood-alcohol content test is administered, the subject's blood-alcohol content may have dropped below the legal limit.
Legal Ramifications
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If your blood-alcohol content drops below the legal limit by the time a blood-based blood-alcohol test is administered, the test would not be able to support an impaired driving charge. You may then wonder if the prosecution could use the breathalyzer test in support of the charge instead. Because of the inaccuracy of breathalyzer tests, if you are prosecuted for impaired driving and the only evidence available to the prosecution is a breathalyzer, there is a good chance you will be found not guilty. Urine tests could go either way, depending on the state and court precedents.
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References
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