Blood testing procedures are entirely different from breath testing measures. For your DUI blood test results to be admissible as evidence, the prosecutor has to demonstrate the reliability of the test by putting forth various witnesses.
For the results of the State’s test to be admissible, the State must show that it was performed in such a way that the results obtained should be considered accurate and that the substance being tested (i.e., blood, breath or urine) came from you and no one else. The first area of proof focuses on whether or not the test machine itself was properly calibrated, and whether or not the test was run correctly by someone capable, trained, and authorized to operate the machine.
Challenging A DUI Blood Test in Court
If the blood test results being used against you were drawn as a part of a medical evaluation following an accident (in a hospital), rather than those drawn at the express direction of the police for evaluation in a crime lab, the testing must still have been done in compliance with the statutory standards for such “forensic” tests.
The second area of inquiry focuses on the State’s ability to establish the chain of custody for your sample. This issue may be raised in virtually all blood test cases due to the fact that any sample of a bodily substance can “decompose” (spoil). This decomposition process can actually generate (create) ethyl alcohol, which is the type of alcohol in all alcoholic beverages. Your DUI attorney focuses on whether the sample was collected properly, whether the sample was stored properly, whether the collection tubes were the correct type required for forensic testing, whether your arm was swabbed with a non-alcoholic pad, when and where the samples were stored in a refrigerated receptacle, whether the nurse or phlebotomist properly inverted the vial of blood before sealing the package for shipment to the crime lab, and similar issues that involve the “integrity” of the sample.
Even when grossly improper handling of your blood sample is shown by your attorney, the lab results may not be automatically excluded from evidence at trial. In some states, any discrepancies in the chain of custody may go to the weight of the evidence, and not cause the lab results to be excluded.
In others, the judge acts as a gatekeeper and decides what evidence is too tenuous to be allowed to be used by the State in its prosecution of a case. In the states that require the prosecution to establish a full and unbroken chain of custody, the lab results may be kept out of evidence. Such an exclusion by a trial court often ends the “per se” alcohol case, due to a “lack of evidence” to support that DUI-DWI charge against you. Such exclusion of this critical evidence in an accident case can cause the State’s entire case to fail.