What Evidence Is Used in a DWI Case with Prescription Drugs?

 Posted on March 28,2019 in DWI / DUI

What Evidence Is Used in a DWI Case with Prescription Drugs?Prescription medications and over-the-counter medicines have side effects that can impede your ability to perform normal tasks. Mixing prescriptions or combining them with alcohol may heighten those symptoms or cause unexpected reactions. It is wise to read the potential side effects when taking a new medication and to see how your body reacts to it before driving. You can be charged with driving while intoxicated if a police officer determines that the effects of a legally prescribed drug impaired your ability to drive.


An arrest for DWI with prescription drugs will likely start the same way as DWI with alcohol. The officer may stop you because you have committed a traffic violation or appear to be driving erratically. During the stop, the officer will look for signs of impairment from your appearance and behavior. Evidence used in cases of DWI with prescription drugs may include:

  • Officer testimony that the defendant appeared dazed or unresponsive;
  • The defendant admitting to the use of prescription medicine;
  • Observations from a field sobriety test; and
  • The results of a blood test showing the presence of drugs.

You cannot defeat a DWI charge by saying that a physician legally prescribed the drug to you. If a prescription drug causes you to reach the legal definition of intoxication, you may be responsible if you drive in that condition and put yourself and others in danger.


Unlike with alcohol, there is no measurable level of drugs in your system that makes you guilty of DWI. This works in your favor with legal prescription drugs because their presence in your body does not prove that you were legally intoxicated. The prosecution must present evidence that your driving ability was impaired at the time of your arrest. You can limit that evidence by:

  • Not disclosing to the officer that you take prescription medication; and
  • Refusing to take field sobriety tests, which are unreliable indicators of impairment.

You can also refuse the blood test, though the officer may compel you to comply by obtaining a warrant. As with any DWI charge, you can contend that the officer did not have reasonable suspicion to stop you or probable cause to arrest you.

Contact a San Antonio DWI Defense Lawyer

A conviction for DWI with prescription medication has the same consequences as DWI with any other substance. A San Antonio DWI defense attorney at the Law Offices of Sam H. Lock can contest the claim that you were legally intoxicated. Schedule your consultation by calling 210-226-0965. 



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