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Blood testing in DUI cases

A common misperception of blood alcohol testing is that the results of the prosecution's test cannot be challenged in court.In reality, a skilled DUI defense attorney who understands both the law and science behind forensic alcohol analysis can do just that.

In many courts, including Scottsdale Municipal Court, blood testing is conducted using a process known as headspace gas chromatography.This technique is designed to ascertain the level of ethanol in a person's blood by measuring that amount of alcohol floating in the air above the blood sample in a sealed vial.Before the "headspace gas" is measured, the test vials are prepared using another machine referred to as a pipetter which is expected to measure precise amounts of blood and another solution into the test vial.If either of these liquids are introduced into the test vial in an improper amount, the test results could be effected.

Reliable blood alcohol testing also requires that the blood be collected, preserved and handled appropriately prior to the testing process.For example, the collection tubes used by the police are supposed to have both an anticoagulant and a preservative pre-packaged inside the tube prior to use.These agents are designed to prevent the blood from clotting and/or decomposing.Even though forensic scientists have repeatedly established that the presence of either decomposition or clotting can artificially increase the results of an alcohol test, police crime labs typically do not conduct any testing to verify that the anticoagulant or preservative is present in the blood sample.

There are many other nuances to blood alcohol testing that must be addressed in order to effectively challenge a blood test in a DUI case.Given Arizona's strictly enforced extreme DUI laws which can mandate a 45 day jail sentence based on a blood test result alone, it is crucial to have the blood test evidence in your case scrutinized and challenged by a knowledgeable and experience DUI attorney.

If you have questions about blood alcohol testing in you case, please contact DUI attorney Joshua S. Davidson today to schedule a free initial consultation.