Retesting Blood From a DWI Arrest in Texas

By Criminal Defense Lawyer Jeremy Rosenthal

(972) 369-0577

You can retest blood from a Driving While Intoxicated arrest in Texas.

In fact, you can even retest it without the prosecution not knowing the results of the retest.

I’ve been blogging lately on expert witnesses and their role in investigation and assistance on the criminal defense team.  Remember, the law encourages defense lawyers to investigate their case without fear they will uncover unfavorable evidence.

How Does a DWI Blood Retest Work?

The blood is typically kept with the police department who originally made the arrest after it is tested by the Department of Public Safety.  They’re not going to hand over the blood to you or your retesting lab as you might imagine.

A lawyer can file an Ex Parte Motion with the Court.  That means “one party.”  A Criminal Defendant is allowed by law to approach the judge without knowledge of the prosecutor when they need to utilize the power of the court for assistance.

Your lawyer does have to convince the court the evidence will be handled appropriately and returned without incident.

The Judge, then, orders the police department (or whomever has the blood) to send it directly to your lab.  After the retest is done, the lab is then ordered to send it back to the police department.

What to Expect From a DWI Blood Retest

Blood oxidizes over time.  This means most retests will show less alcohol in the system.  However, retesting is more than a parlor trick.  Studies have been done on how much oxidizing should take place and if a blood retest shows a significantly lower result then the original – it can suggest the original test was done improperly or the blood was mishandled at some unknown point.

Can You Retest to Make Sure it is the Same Person?

Some of my clients fear they mixed up their blood at the lab with someone else.  Anything is possible.  This would require a DNA test.  These can be done too but they are far more expensive.

The Prosecution Won’t Know?

The prosecution could likely discover the police were ordered to ship it to an independent lab. And they can probably guess why.  But they’re not entitled to know the result of the retest unless Defense chooses to disclose it.  Further, the Defense lawyer would not allow the prosecutor or anyone to reference the retest if the case went to a trial.  In most instances when we reveal the blood was retested – it actually comes as a surprise to most prosecutors.

*Jeremy Rosenthal is Board Certified in Criminal Law by the Texas Board of Legal Specialization.  He is recognized as a Texas Super Lawyer by Thomson Reuters.

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