Home » Blog » DWI / DUI » Virginia DWI defense lawyer uses science to challenge breath testing

Virginia DWI defense lawyer uses science to challenge breath testing

Call Us: 703-383-1100

Virginia DWI defense lawyer uses science to challenge breath testing

Virginia DWI defense lawyer on using science to challenge the so-called breath testing science

Virginia DWI defense lawyers not only can incorporate preparation and persuasion approaches that apply to most criminal defense work, but also must add addressing, analyzing, and disintegrating scientific evidence. As a Fairfax criminal lawyer, I know that the latter Virginia DWI defense approach is a variation on the essential criminal defense approach of doing the same with all scientific, forensic and technical evidence in any prosecution, including challenging drug testing in drug cases; taking apart the DNA evidence in murder and other cases; challenging scientific analysis of cause of death; challenging fingerprint analysis in cases where the perpetrator is not otherwise known; raising psychological, cognitive, and cross-racial issues affecting visual identification of a stranger; and deconstructing the numbers in financial fraud and other theft-related cases.

Criminal defense lawyers must deal with science in defending against Virginia DWI prosecutions and numerous other types of cases

Anyone going to law school to escape science and math are in for a rude awakening that criminal defense requires applying such skills. Fortunately for me as a Virginia DWI lawyer, I started early on to understand biological science that is essential to my criminal defense work, going back as early as when I joined my high school paramedics group, where I learned how to use a sera lancet to draw blood from a person’s finger and to analyze it, to examine urine, to check basic bodily functions, and to apply first aid and administer cardiopulmonary resuscitation. That was followed by a two-year stint earlier in my lawyer career at a personal injury law firm, where I learned all the better to obtain and analyze complex medical records and to deal with physicians and other medical professionals, and to deal with them as expert witnesses through direct and cross examination. Further on the technical knowledge side of criminal defense, I got a huge leg up on challenging any theft or financial crime through my year before law school with a major Wall Street bank as a financial examiner/auditor. Below is information on challenging Virginia DWI case science.

Virginia DWI lawyer on digging beyond the certificate of analysis on challenging BAC evidence

Most Virginia DWI prosecutions involve submission to a breath test on the Intox EC/IR II machine to get a blood alcohol content (BAC) reading. I have written here and elsewhere about how flawed such “science” is, but unfortunately the Virginia Code and appellate court caselaw give much deference to the commonwealth’s Department of Forensic Science to select the BAC breath testing equipment, and the DFS has selected the Intox EC/IR II equipment. A Virginia DWI lawyer needs both to carefully analyze the certificate of analysis spit out by the Intox EC/IR II machine (see a sample certificate of analysis here) to get further to the heart of the breath testing data, as discussed below.

While we are discussing the certificate of analysis, take a look at the line with the pre-printed phrase RESULTS: TIME SAMPLE TAKEN. As discussed here and elsewhere by me, the DFS instructs to wait at least twenty minutes to reduce the amount of mouth alcohol, because post-arrest breath testing is supposed to test for deep lung alcohol. However, the actual time that the Virginia DWI defendant started blowing into the machine may have been earlier, and that will be shown on the more detailed data shown below. Also look carefully lower down to the left in the certificate of analysis box that says BREATH TEST OPERATOR. Does that box contain the breath test operator’s signature? Once in a blue moon, the operator forgets to sign it. My argument is that such an omission is fatal to allowing the breath test results into evidence at trial, especially when considering the number of avenues that the Virginia Supreme Court has foreclosed in Fitzgerald v. Commonwealth for the defense to bring such attacks as precluding breath testing results when the prosecutor does not present proof that the Intox EC/IR II was within its certification period, nor to preclude BAC evidence in Virginia DWI cases if the prosecutor does not first show that the machine was using an unexpired dry gas standard, which is a control mechanism used to determine whether the machine is working for analytical purposes.

How to obtain and analyze the more detailed DFS data in a DWI case

Here is my standard letter for ordering DFS BAC data in Virginia DWI cases. Much of that data also may be obtained online here, but relevant portions of the data are more likely to be admitted into evidence at court when offered by the defense when the data is is faxed or mailed back from the DFS with the signature of the appropriate records custodian or other DFS official. I use both approaches in obtaining such data.

How to analyze the breath testing result page in the detailed DFS data

Virginia DFS breath test data sheet

Virginia DFS breath test data sheet

Here is a Virginia DFS breath test result data sheet, both in jpg and pdf format. Let us look at the bottom result from October 14, 2019 in this Virginia DWI case, listing the first time as 6:14 a.m. Important elements to look at include the second column, which starts with DIAG, which means diagnostics. Below that is BLK, which means air blank check. Below that is CHK, which means the check of the dry gas standard control mechanism. Next we see SUBJ which means usable breath test reading for the testing subject, which here is 0.137. Further down, we see two minutes after the first usable breath test reading a subsequent breath test jumping by 0.016 to 0.153, which helps show how questionable these breath testing machines are. Further down, we see that the defendant actually blew four times into the machine in this Virginia DWI case, with only four good readings.

This is the first of a two-part article. In the next article, we will review how this and other data can help a Virginia DWI defendants.

Fairfax DWI lawyer Jonathan L. Katz pursues your best defense against Virginia DWI, felony and misdemeanor prosecutions. Call 703-383-1100 to schedule your free in-person consultation with Jon Katz about your court-pending case.