Intoxicated means: not having the normal use of mental or physical faculties by reason of the introduction of alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body. -- Texas Penal Code Sec. 49.01(2)According to the DWI statutes in every state in the US, a motorists is presumed intoxicated if he has an alcohol concentration of .08 or higher. But what about motorists arrested for DWI who have prescription medications in their systems?
Under the Texas DWI statute a motorist can be intoxicated by drinking alcohol, ingesting illegal drugs or taking legally prescribed medicines. A breath test will only show the presence, or absence, of alcohol. Only a blood or urine test will detect the presence of any other substances.
A blood test may show that a motorist had marijuana or cocaine in his system -- but that blood test doesn't say when the driver ingested those drugs or whether the amount found in his system was intoxicating. The same holds true with prescription medications. Due to the chemical makeup of prescription drugs, the effects of a medication may be different from person to person. Then there's the synergistic effect of drugs with each other -- it's the reason doctors ask patients if they are taking any other prescription medications before prescribing something.
Many law enforcement agencies have so-called drug recognition experts (formerly known as drug recognition evaluators) who swoop in with a battery of "tests" to determine whether a motorist suspected of DWI was intoxicated by some substance other than alcohol. Their conclusions, however, are generally determined by what the motorist admits to taking. If the motorist admits to smoking pot then driving, the DRE concludes that he was intoxicated by use of marijuana. Gotta love it when it all comes together like that.
The question becomes murkier when a motorist has only been taking prescription medications, as noted in this New York Times article. What were the medications? How do the drugs interact with each other? Were there warnings on the bottle about the effects of the drug? What dosage was the motorist taking? Was there alcohol in the driver's system? What about illegal drugs?
Chances are members of the jury panel are taking prescription medications? How would they feel if they thought they could be arrested for driving while intoxicated after taking their medicine?