A growing number of people are arrested for driving under the influence of prescription painkillers, over-the-counter sleep aids, and other legal drugs. While it is legal to take these substances in Texas, provided that one has a prescription if needed, it is illegal to drive under the influence of these drugs under Texas Penal Code 49.04(a). California has a similar law, and in 2015, authorities charge a man with driving under the influence of caffeine. Although prosecutors later dropped that charge, the proceeding illustrates the broad laws in both the Golden State and the Lone Star State.
What must prosecutors establish beyond a reasonable doubt to obtain convictions in these Texas cases?
Step One: Substance
In some states, the defendant must be under the influence of a controlled substance for DWI-drug charges to stick. “Controlled substance” usually means any legal or illegal drug except tobacco. But in Texas, any substance will do, provided that prosecutors can prove consumption. Such proof includes:
- Direct Evidence: Probably by about 2020, officers may use Q-tip swipes, similar to the DNA tests administered in some child custody cases, to determine the presence of drugs. A viable marijuana Breathalyzer may be even closer than that. Officers may also order blood or urine tests, but these invasive tests require search warrants if the defendant does not consent.
- Circumstantial Evidence: Open pill bottles in the car, drug paraphernalia on the defendant’s person and the defendant’s statements to officers may suffice to prove drug consumption beyond a reasonable doubt.
Officers at least need probable cause to believe that the defendant had recently consumed an impairing substance before they can legally proceed to the next phase.
Step Two: Impairment
Under current law, prosecutors may only use circumstantial evidence to prove impairment. There is no provision in 49.04 or elsewhere which states that a person is impaired as a matter of law if there is more than X amount of Y substance in the person’s bloodstream.
As technology advances, the legislature will probably add such a provision. Expect a battle here especially with regard to marijuana, because there is no consensus on what THC level constitutes impairment, or even if this substance impairs drivers at all.
Circumstantial evidence in Texas DWI-drug cases usually means the three approved field sobriety tests, which are:
- Walk-and-turn (a/k/a heel-to-toe walk),
- Horizontal gaze nystagmus, and
- One-leg stand.
Other circumstantial evidence may be admissible as well, such as unapproved field sobriety tests and physical symptoms, such as the finger-to-nose test and bloodshot eyes, but this evidence is quite weak.
Contact an Experienced Attorney
DWI-drug cases rely almost exclusively on circumstantial evidence. For a free consultation with an experienced criminal defense lawyer in Houston, contact the Law Office of Jim Medley.