DWI under the influence of drugs is different from DWI related to alcohol. It can often be harder to prove guilt beyond a reasonable doubt, for one thing. Furthermore, there are many prescription drugs as well as illegal drugs that could result in a person getting a DWI. Drug-related DWI is more difficult to prove. One reason is that there is not currently a specified limit for any drugs, like there is with alcohol. There are many illegal drugs that can result in a DWI, such as Marijuana, Cocaine, Heroin and others. But, taking prescription drugs can leave drivers equally vulnerable, even if you have a valid prescription and are taking the prescribed amount.

What is the Legal Limit?

Most people are aware that it is illegal to drive with a blood alcohol concentration of over .08 percent. No such limit exists for any drugs, whether they are illegal or prescription drugs. For this reason, it can be more difficult to prove that a person is guilty of DWI beyond a reasonable doubt. In every case, that is what the state of Texas must prove for you to be convicted.

Texas Penal Code Section 49.04 DWI

In Texas, it is against the law for someone to operate a motor vehicle if they have lost control of either their mental or physical faculties because of intoxication. This is according to Section 49.04 of the Texas Penal Code. The State will attempt to prove that you have lost control of both your physical and mental faculties. Police will almost always get a blood test—especially if a breath test is refused or the breath test comes back negative for alcohol. Your blood will be tested for a series of controlled substances and prescription drugs. Then the medical examiner will offer his or her opinion that you were intoxicated while driving, even though there is no per se limit.

Frequently Abused Prescription Drugs

Here is a list of the prescription drugs that can result in a DWI arrest. If in fact you have been arrested, you should contact a Fort Worth DWI lawyer to discuss your defense.

Here are the categories of prescription drugs I see most often:

  • Central Nervous System Depressants—benzodiazepines and barbiturates are prescribed for sleeping disorders and anxiety
  • Opioids—these are synthetic narcotics not derived from opium, and they are prescribed as painkillers
  • Stimulants—most often prescribed for ADHD, but also increasingly to combat obesity.

Examples of Central Nervous System Depressants

  • Valium
  • Xanax

Examples of Opioids

  • OxyContin
  • Hydromorphone
  • Demerol
  • Methadone
  • Morphone

Examples of Stimulants

  • Ritalin
  • Adderall
  • Dexedrine

Meet the Drug Recognition Expert

Simply put, the drug recognition evaluation is a system of tests designed for cops by other cops. There is little scientific backing for the conclusions, and the examiner is neither a scientist nor a medical expert.

Here’s how the scenario often plays out. When you are pulled over and arrested for suspicion of DWI, you will either consent to take a breath test, or you will be taken to a hospital and your blood will be drawn. If you consent to a breath test, and the results come back negative for alcohol, police will begin to suspect drugs, and a drug recognition evaluation will begin. This is a series of tests that are crudely designed to determine which category of drugs might be impairing you. Vital signs are measured and cognitive tests are conducted. As one attorney once memorably put it to me, the drug recognition expert throws a dart at the wall, then draws the bullseye around it, and then the rest of the dartboard. I have found this to be true.