FJ Journal No. 4 - Driving While Intoxicated - Part 3: DWI Breath and Blood Testing

5/20/2024

             Welcome back to the FJ Journal! This will be the last article in our DWI series for the time being, and it will briefly cover some of the issues surrounding the testing of breath and blood samples in DWI investigations. While it is important for attorneys to be informed as to the science behind the tests used to examine these samples, such a discussion would be outside of the scope of this format. Therefore, the primary aim of this article will be to inform the reader regarding the law and their rights as they pertain to the acquisition and testing of these samples.

Since we’re discussing biological samples obtained from a live person, some might be surprised to hear that Courts examine the legality of these police procedures under the legal umbrella of the Fourth Amendment. That’s right: the Constitutional protection against unreasonable searches that most commonly prevents police from searching containers, vehicles, and homes unless they first go through the process of obtaining a warrant. Warrants can be problematic for the police in DWI cases for reasons that will be discussed in the section of this article pertaining to blood samples. Courts have decided that “searching” inside of a human body is not much different. With this added context, you might begin to foresee some of the issues that might arise during these invasive procedures.

             Toward the end of a DWI investigation, most police officers will ask the subject of the investigation whether they are willing to provide a sample of their breath or blood for the purpose of testing. Unfortunately, unlike the Standardized Field Sobriety Tests, while you can refuse to provide a sample of either, the Texas Transportation Code does impose a penalty for this refusal in the form of a longer driver license suspension.[1] This is known as the Texas Implied Consent law, which establishes, among other things, that you have already consented to provide a sample simply by virtue of operating a motor vehicle on Texas roadways. I should also note that refusal to provide a sample will not necessarily prevent the officers from obtaining a sample through other means, which will be discussed later in this article.

Given the harsh suspension penalties, it is understandable that most people would agree to provide a sample of either breath or blood. This is usually referred to as “pure consent” to the search. A person’s consent completely waives the usual requirement that the police obtain a warrant before performing a search. However, many officers often make mistakes in the language they use request this sample from the driver, which can result in the test results being inadmissible in court. Determining whether this applies to your case requires a careful examination of the timeline of the investigation which is often better left to an attorney familiar with your case.

Breath Samples

In the majority of DWI cases, a person consents to providing a breath sample, since it is usually considered as less invasive than being poked with a needle to draw blood. The old handheld breathalyzer popularized in the media are no longer the gold standard, so these days obtaining a breath sample will require a trip to the police department, where they house and maintain large breathalyzer devices. A discussion of the science behind these devices is outside of the scope of this article, but I can summarize by stating that it is sound and accepted in courts throughout the United States.

Generally, to operate the station breathalyzer device an officer is required to go through training and be certified in its operation. In large counties, police departments will have staff dedicated to operating the breathalyzer. This training or specialization is an important aspect of your case, since there are procedures that must be followed for the results of the breath test to be valid. One example of such a procedure is the 15-minute observation period prior to taking the test. Without this observation period, there is a chance that the breath test results will be inadmissible at trial. Additionally, breathalyzers must be calibrated at specific intervals to remain accurate, something which is not always done. As simple as it sounds, determining whether this is an issue in your case may still require the assistance of an attorney.

Blood Samples

While there are some that will voluntarily provide a sample of their blood at the officers’ request, the vast majority of blood samples are obtained by the officers through the use of a search warrant. Like every other warrant, this requires that the officer write out a probable cause affidavit and present it to a magistrate or judge for approval. In most counties, this process can take up time that is very valuable in a DWI investigation. Unlike almost every other type of crime, DWI cases are unique because the most reliable evidence, the blood alcohol content, is self-destructing. It is for this reason that large counties have magistrates around the clock to review warrants.

As those better-versed in legal concepts will imagine, the necessity of a warrant opens up certain possibilities to attack a DWI case. Search warrants must meet established and strict requirements to be valid. An comprehensive discussion of search warrants will likely be the subject of a future article. For purposes of this article, I encourage everyone reading this article to consult with our firm to have an experienced attorney review the search warrant involved in your case for its validity.

The issues with blood samples do not end with the search warrant. Once the officers have executed the warrant and obtained a sample of your blood, they must then send it out for testing. In small counties this will often require that officers send the blood sample to a lab elsewhere. Large counties usually have a forensic scient institutions that perform the testing of blood samples, among other services. Here again, this testing opens up new avenues of attack. The science behind the testing of a blood sample is sound and widely accepted, but, unlike breath samples, the documentation required is exponentially more extensive. All of this documentation is necessary to ensure that the result of the testing is valid, and thus must be carefully examined.

Finally, the DWI investigation has come to an end. While officers often promise to release an individual if they test below the legal limit, I have yet to see an officer hold up his end of the deal. For an overwhelming majority of people, once officers have acquired a sample of either breath or blood, they will have DWI charges filed and the individual will be kept in jail until the individual can see a judge or magistrate to set a bond and bond conditions. The subsequent prosecution, options, and trial are better left as the subject of another article.

That will conclude FJ Journal No. 4. As mentioned above, this will be the last article in the DWI series for now. If you have followed and read this series: thank you! I am confident that you are now more knowledgeable of DWI investigations and law. The next articles will cover other prevalent criminal offenses and your rights as it pertains to those offenses. See you then!

Arturo J. Reyes
Attorney and Counselor at Law

[1] Tex. Trans. Code § 724