What do I need to know if my DWI case involves drugs?

If you have been arrested for DWI in Texas and it is alleged that you had drugs, and not alcohol, in your system, there are several things to keep in mind. Law enforcement has developed unique tests to try and determine intoxication by substances other than alcohol. Also, DWI drug cases can be more complicated than DWI cases involving intoxication by alcohol due to the fact that drugs are metabolized in a different way than alcohol. A DWI attorney should also understand that the State will try to present evidence that presents different issues than in a DWI involving alcohol.

The first thing to keep in mind is that in Texas, the law is concerned with whether a person was under the influence at the time of driving. This means that the State has to introduce some type of quantitative estimate of what a person was under the influence when he or she was driving, not when the blood was actually drawn. The process by which this is done is known as “retrograde extrapolation,” which simply means to go back in time to estimate (i.e., extrapolate) what it would have been.

With alcohol, it is sometimes possible to estimate what a person’s blood alcohol content was at the time of driving. For example, if a person is stopped at 8pm and given a blood test at 9 pm, an analyst can, with certain information, perform a retrograde extrapolation that would allow her to estimate what the blood alcohol content would have been one hour earlier. This process is not easy and any evidence of a retrograde extrapolation should always be challenged. However, performing a retrograde extrapolation is easier with alcohol then with drugs because alcohol is metabolized in a more linear or predictable way.

One tool that law enforcement officers use to help determine whether a driver is under the influence of drugs or alcohol is known as the Drug Recognition Expert (DRE) evaluation. The DRE was developed in the 80s and is used nationwide today. Police claim that the DRE can be used to determine whether a person is impaired, if the impairment is due to some substance other than alcohol, and what the category of drugs that has caused the impairment may be.

The DRE test is standardized (meaning it should be done the same every time) and is essentially a 12 step visual, mental and physical examination designed to rule out and supposedly identify the class of drug suspected in the case. The DRE training materials identify 7 different DRE drug categories:

  • Central nervous depressants such as tranquilizers and barbituates.
  • Central nervous stimulants, such as cocaine and amphetamines, including drugs like Adderall and methamphetamine.
  • Hallucinogens like LSD and psilocybin (aka “magic mushrooms”).
  • Dissociative anesthetics like PCP.
  • Narcotic analgesics which includes natural and synthetic opiates.
  • Inhalants which includes a variety of vapors that are inhaled.
  • Marijuana, including edible and smoked marijuana.

It is critical that a criminal defense attorney defending a DWI where a person is alleged to be under the influence of drugs understand the DRE examination and its limitations well. The DRE has been shown to have a highly questionable ability to predict the class of drugs at issue in a DWI. Since the DRE is standardized, it should be administered the same way every time, otherwise it should be challenged as inadmissible. It should also be noted that unless the witness is properly qualified as a DRE expert, Texas cases say he or she cannot offer opinion evidence of what he believed a person was under the influence of in a DWI case.

A DWI attorney should not only the challenge the administration of DRE testimony, he should even try to prevent it from being heard by the jury in the first place. The Rules of Evidence, which courts must follow before they allow testimony regarding the DRE, state that the evidence or technique should actually be reliable, relevant and helpful to the jury and allow the officer to do what he claims it does. At least some courts have kept DREs out on his basis, coming to the conclusion that the witness presented was not an expert, did not administer the DRE properly and that as a result, the offered testimony would not be relevant or helpful to the jury.

In addition to the DRE, blood tests are commonly used by the state to attempt to show that a person was under the influence of a substance other than alcohol. But as noted above, this can be difficult for the State as drugs usually do not metabolize in a predictable way, when compared to alcohol. For example, a person could have smoked marijuana several weeks before being arrested for DWI, and yet still show marijuana metabolites in his blood. Obviously, this does not mean that the person is under the influence of marijuana at the time of driving. A DWI attorney should understand the science relating to the way drugs different classes of drugs are metabolized and what metabolite levels tell us about whether a person is actually under the influence.

Attorney Jose Ceja is well versed in the science of DWI drug cases and has the knowledge to properly interpret, analyze and challenge all parts of the State’s evidence. As should be clear from this article, DWI drug cases present many complexities that an attorney should be prepared to handle. If you or a loved one is charged with DWI involving drugs anywhere in the Houston area, attorney Jose Ceja is an excellent choice. Call today for a free consultation.