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Technical challenges to BAC testing covered by Virginia DUI Lawyer

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Aug 30, 2019 Technical challenges to BAC testing covered by Virginia DUI Lawyer

Technical challenges to BAC testing covered by Virginia DUI Lawyer - Photo of liquor glass and keys

Technical challenges to BAC testing covered by Virginia DUI Lawyer

Technical challenges to breath and blood alcohol testing addressed by Virginia DUI lawyer

Technical challenges to breath and blood testing are very important for defending against DWI prosecutions. As a Virginia DUI lawyer, I prepare these challenges early on. They include the following:

Obtaining and challenging essential technical data for Virginia DUI defense in breath testing cases

With both breath and blood testing technical challenges for Virginia DUI defense, it is important timely to file a request for and objection to the certificate of analysis.

The breath testing data as to the machinery used and the technical specifics about the testing with the Virginia DUI defendant should be obtained both by a letter request to the Department of Forensic Science (DFS) and online data check.

Obtaining data for Virginia DWI blood draw cases

For technical challenges in Virginia DUI blood draw cases, it is important timely to seek an order for the transmission of a sample of the blood to a private testing laboratory, to check the accuracy of the DFS’s testing.

For such technical challenges, the criminal defense should select a suitable laboratory for conducting the independent blood testing, taking into consideration the lab’s responsiveness, accuracy, report format, confidentiality, and accreditation or certification to make its reports admissible in court without a witness.

The defense should subpoena the DFS data involved in its testing of the DUI defendant’s blood.

Virginia DUI defensive use of margins of uncertainty and presumptions

The Virginia DFS will always assign a margin of uncertainty for blood alcohol content (BAC) testing in DUI cases. For breath testing technical challenges, the DFS will provide on request the Certificate of Instrument Accuracy, which will assign a margin of uncertainty of + /- 0.004 for BAC results under 0.15, and + / – 0.008 or 0.009 for results of 0.15 or higher. For a blood test BAC of 0.12, for instance, the assigned margin of uncertainty may be around + / – 0.007.

A qualified private forensic toxicology expert can be expected to testify in such technical challenges that scientific soundness calls for substracting that margin of uncertainty from the BAC test result. Such subtraction can mean much for the defendant whose BAC test is right on or only a little above the border between eligibility for a particular mandatory minimum sentence or presumption of being culpable or not, or having no presumption thereof.

Note that the current DFS  breath test operators manual provides for at last two breath test samples to be provided by the suspect, and that the final BAC “result is the lowest of the 2 or 3 samples provided by the subject, truncated to 2 digits past the decimal point.” I would argue in such technical challenges for applying the same truncation in blood testing cases when addressing the above-addressed presumptions.

Challenging the reliability and integrity of the equipment used for DUI case breath testing, and the testing procedures

The criminal defense should be ready to discover and challenge irregularities with the conduct and timing of certification and calibration of breath testing equipment. See here for more technical challenges that can be made against breath testing in Virginia DUI cases. See here and here for more available challenges against blood testing.

Fairfax, Virginia DUI lawyer Jonathan L. Katz pursues your best defense against felony, misdemeanor, and DWI prosecutions. For a free confidential consultation with Jon Katz to discuss your pending criminal court case, please call 703-383-1100. 

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