The Law Firm of Joseph Lassen‘s San Antonio Legal Blog

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Flawed test tubes compromise thousands of Texas DWI cases

A bad batch of test tubes shipped out two years ago could affect more than 2,700 drunk driving arrests and DWI convictions across Texas.

According to a news investigation, the tubes made in 2019 were for use in DWI blood tests. The tubes were recalled, but not all crime labs and police agencies learned of the recall in time. They used the flawed tubes in drunk driving blood tests.

The recalled tubes lack a preservative that keeps the level of alcohol in the blood sample from changing before lab testing takes place.


It isn’t clear if any San Antonio DWI arrests involve the recalled tubes. The Dallas-Ft. Worth station said it surveyed law enforcement agencies in its area, as well as large police departments across the state. Their investigation doesn’t mention San Antonio.

The report says the recalled tubes were used in at least 2,760 DWI arrests.

In many cases, a driver suspected of DWI is asked to perform field sobriety tests and then asked to submit to a breath or blood test to determine their blood alcohol concentration (BAC). If the result of the blood test shows a BAC of .08 percent or higher (the legal threshold in Texas), the driver will be arrested for DWI.


“The recalled tubes have raised concerns among law enforcement officials and defense attorneys that some accused drunken drivers could walk free, or that others could be wrongfully convicted,” the news report stated.

Dr. Peter Stout, CEO of the Houston Forensic Science Center and the head of the Texas Association of Crime Lab Directors, said “there’s no question some of these were used in actual cases. And that has created some real issues for us and for the entire court system.”


Arlington Police Chief of Staff Chris Cook said news of the recalled tubes was “frustrating” and “disheartening.” His department used the tubes in 61 cases.

The Texas Department of Public Safety said its crime labs have tested blood in the recalled tubes in at least 290 cases.

The NBC TV station said its reporters found 49 cases in which recalled test tubes were used even after police departments had been informed of the recall.

Studies have shown that if the preservative is missing, alcohol levels are likely to go down rather than up. It’s rare for alcohol to increase, according to the news report. However, the recall notices sent by the manufacturer stated that blood alcohol levels could be “either falsely low or falsely high” if the preservative was missing.


A former prosecutor said he expects that defense attorneys will use the statement in the recall notice “very aggressively. They’re going to use it to suggest that something might have happened. They’re going to use this to suggest that the system’s not perfect.”

There’s little doubt that those arrested for DWI in 2019 and their legal representatives have good reason to look back at the evidence.