Scottsdale Criminal Defense Attorney
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Breath & Blood Testing

Although breath testing is less expensive and provides quicker results, it is considered less reliable than a blood test for purposes of determining an individual’s BAC. For this reason, officers will seek a blood sample when making a DUI arrest. Prosecutors also relish the opportunity to present evidence of blood testing in court because it allows them to call the criminalist who tested to blood as a trial witness. Ordinarily, these individuals are qualified as experts by the judge and permitted to testify about DUI related topics completely unrelated to the test of your blood.

Nevertheless, blood testing is not infallible. A skilled attorney who is knowledgeable in both the law and science behind forensic alcohol analysis can make a difference.

A currently evolving issue in Scottsdale DUI law is the collection on blood samples by police officers. Arizona law requires that blood samples be taken by a medically qualified individual. Until recently, Scottsdale police officers would have a nurse or other independent medical professional collect the sample. Today, however, many Scottsdale DUI officers have become certified as phlebotomist and are collecting blood samples themselves.

Contrary to popular belief, improper collection of a blood sample can compromise the validity of any future laboratory testing that may be conducted. If, for example, the skin was not sterilized before insertion of the needle, microscopic fungal organisms can get drawn up into the collection tube with the blood. Some of these organisms can convert your blood into alcohol and artificially inflate your BAC. The test could also be invalidated if the officer uses an isopropyl alcohol pad to sterilize the collection site.

Common Blood Testing Defenses

In addition to challenging the credentials of the police officer and the manner in which they took your blood, Scottsdale DUI Lawyer Joshua S. Davidson will thoroughly investigate your case for any other grounds to challenge your blood test results.

Chain of Custody

It is not uncommon for a blood sample to pass through the hands of several different people between the time it is obtained and the time it is testing. Moreover, Scottsdale crime lab technicians tests dozens of samples during each “run”. This process is obviously fraught with the risk of a sample being mishandled. Scottsdale DUI Attorney Joshua S. Davidson will closely analyze the chain of custody record and investigate any irregularities.

Condition of the Collection Tube

The blood kits used by Scottsdale DUI officers include sterilized vacuum tubes which contain an anticoagulant and a preservative. Because the vacuum is slowly compromised and subjected to the exposure of external contaminates over time, each tube has an expiration date by which it must be used. If the police in your case used an expired tube or failed to document the expiration date, a Scottsdale DUI defense attorney may be able to keep you blood test results out of court.

Were Proper Testing Procedures Followed?

Even if the blood is properly obtained and handled, it still needs to be analyzed by the criminalist. In Scottsdale, the preferred method of testing is gas chromatography. Mr. Davidson will closely review the records and chromatographs from your test together with any calibration tests that were conducted. A pretrial defense interview of the criminalist who actually tested your blood will also be conducted. As a Scottsdale DUI Lawyer who understands the legal and scientific complexities of blood testing, Mr. Davidson will subject the prosecution to the highest levels of scrutiny when challenging your blood test results.

When you or a loved one has been arrested on a DUI charge, emotions run high and questions mount as you face the legal process. Worries about a negative outcome in your case and how it will affect your life sometimes drown out all other thoughts. Like any other criminal arrest and case, mistakes can be made in this process that could be key in your defense. No law enforcement officer, testing equipment or other sobriety test has perfect and definitive results. For help in navigating these sometimes confusing legal waters, it could be in your best interest to contact an attorney as soon as possible. Time can be of the essence in a DUI case.

Breath testing is one of the most commonly used forms of testing blood alcohol levels and in making DUI arrests. These machines are far from perfect and can produce erroneous results. Since 1937 when the first device to test blood alcohol levels was introduced, constant improvements have been made and new devices released to attempt to improve the reliability of results. But even today, breath testing machines are subject to operator error, internal malfunction, interference from other devices, and problems arising from poor maintenance.

Although stationary testing devices at a police station may provide more reliable results than a field-operated machine, or Preliminary Alcohol Screening (PAS), all breath-testing machines make certain assumptions about test subjects that may be false. Breath testing is not a "one size fits all" affair, but is often times treated as such.

Enlist Quality Representation

Procuring an excellent criminal defense attorney in Scottsdale is crucial, as he can help delve deeper in possible mistakes made in your case and use them in your defense.

Joshua S. Davidson has been providing top-notch legal representation in DUI defense cases for years, gathering on his experiences as a former DUI prosecutor. He can offer you comprehensive experience and a level of service you deserve and respect.

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