Testing for BAC in Arizona DUI

In Arizona, BAC (Blood Alcohol Content) is the criteria on which your DUI case may depend, a higher BAC will result in harsher penalties. Usually it is done by either breath testing or running blood tests in Arizona DUI investigations. So with your future at stake it is important for you to understand how BAC is measured, as even a fraction of deviation in the results may have grave consequences for your future life.

Preliminary Breath Testing

The preliminary breath test (PBT) is a handheld model device used by the police officers to check the BAC of a suspect at a DUI road block or in a DUI stop. As a result, these machines are not considered to be that accurate, in Arizona, the PBT result is generally not admissible as evidence in the court. Since the prosecution cannot use the PBT results against you in an Arizona DUI trial, you can refuse to submit to this test.

The fact is that the police officers often use the preliminary breath test as a leverage to establish probable cause to arrest a person. That means that even if you pass other field sobriety tests, but show a higher or close to the legal limit on the PBT, the officer can justify arresting you despite your passing the other field tests.

Given the inaccuracy of PBT devices, even if you know that you are within the legal limits do not blow it, as you will be giving the officer a cause to arrest you. If you get arrested for a refusal even then you stand a better chance by way of a blood test.

Evidentiary Breath Testing

The more reliable breath testing machines are commonly known as breathalyzers or intoxilyzers, in Arizona the newer version of Intoxilyzer machines “Intox” are being used (these are not portable units). These are capable of printing results, and their results are deemed admissible evidence throughout Arizona.

Blood Tests

A blood test can be more accurate than a breath test but can be subject to complex procedural fo rmalities. Due to the inaccuracy and biased results of Intoxilyzer machines many police jurisdictions in Arizona are shifting to blood tests for DUI cases.

The reason why some jurisdictions in Arizona have not switched from breath to blood tests in DUI cases is the cost and time involved. While an Intoxilyzer test result may be generally admissible into evidence without an expert’s opinion, the blood test results require an expert in court in addition to lab personnel for verification of sample custody and authenticity.

A blood test no matter how accurate, does have room for errors, and can be challenged on the following grounds:

  • If the blood sample was not taken by qualified medical personnel
  • Proper procedure was not implemented while drawing the sample
  • If the blood sample was subject to any contamination (yeast)
  • If an alcoholic swab had been applied to sterilize the site body used for drawing the blood sample
  • In case the lab equipment had not been sterile that had been used to collect the sample
  • Though this may be rare but due to the large numbers involved there can always be a possibility of a sample mix-up

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