DUI Blood Testing

Pima County / Tucson DUI Blood Testing

Background

A growing trend in DUI investigations is blood testing.  More and more law enforcement agencies are drawing and testing blood instead of using traditional breath testing devices.  In Arizona, not only is law enforcement increasingly going to blood testing, but in conjunction with this, officers statewide have been personally drawing blood at investigation sites instead of transporting the arrestee to a medical facility.

In Pima County, the Sheriff's Department exclusively uses blood testing in its DUI investigations.  Normally, officers use special vacuum tubes containing a preservative and anticoagulant to collect the blood.  If the tubes lack either a preservative or anticoagulant, the validity of the blood test will be highly suspect, if not outright inadmissible.  The preservative is supposed to prevent bacteria, fungus, or yeast, from growing in the blood.  Fungus or yeast growth can lead to neo-genesis of alcohol in the blood just as yeast produces alcohol in fermenting grape juice.  If no anticoagulant is present in the tube, the blood will clot.  Clotting severely hinders the ability of the crime lab to accurately test the blood.

Challenging Blood Test Results

One of the reasons law enforcement has embraced blood testing is they perceive it to be less susceptible to defense attorney challenges.  While challenging the accuracy and reliability of blood test results, as a general rule, is more difficult than challenging breath testing, blood testing is not without faults.  One of the problems with blood testing is that the process is more complicated and there are more opportunities for mistakes to occur. The following are some, but certainly not all of the possible issues that may be relevant in a blood test case:

Collection and Storage of Blood Evidence

  • Were the tubes expired? Were the right type of tubes used? How was the tube handled and stored prior to the draw?
  • Who drew the blood? (was it a cop purporting to be qualified, or a true medical personnel?)
  • Where was the blood drawn - outside at the scene, or at a medical facility?
  • Did the person drawing the blood follow proper medical procedures?
  • Did the person drawing blood properly invert the tubes to mix the blood with the chemicals?
  • Was the blood, once collected, handled in an appropriate manner and timely transported to the evidence refrigerator, or did it sit around in a hot vehicle for hours?
  • Was the chain of custody properly preserved and documented ensuring that the blood was not tampered with?

The Testing Process

  • Who tested the blood?  Were they qualified to test the blood?
  • What method was used to test the blood?  Were the protocols faulty?
  • What type of equipment was used?  Was the equipment used the right type of equipment, and was it in proper working order?
  • Did the analyst follow the protocols? What type of controls and calibrators were used?  Were any of them expired?  Did any of them read out of tolerance?
  • Did the testing equipment report any errors in the testing process?
  • Did the maintenance records show any problems with the testing hardware?

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