Facing a driving while intoxicated (DWI) charge can be deeply jarring when you simply took medication prescribed by your doctor. You likely followed the label exactly, with zero intention of breaking the law. However, Missouri law does not limit DWI charges to alcohol. A valid prescription will not shield you from liability if the medication impairs your driving.
How Missouri treats prescription drug impairment
Missouri law states that you commit the offense of DWI if you operate a vehicle while in an “intoxicated condition.” State law defines that condition as being under the influence of alcohol, a controlled substance, a drug or any mix of these substances. A prescription drug may support a DWI charge when it affects your ability to drive safely.
The main issue is how the drug affected you and not necessarily whether a doctor approved it. Some pain management pills might make you drowsy. Sleep aids could slow your response time, while other medicine may blur your sight or affect your judgment.
How officers look for drug impairment
Law enforcement may watch how you drive, speak and respond to questions. The officer might also check your balance or eye movement. A breath test could show little or no alcohol, but that result does not end a drug inquiry.
A specially trained officer may look for signs tied to drug use through a set review. When they suspect drug impairment, they could request a breath, blood, saliva or urine test. A lab then checks the sample for alcohol or drugs.
Prepare for the next steps
If you find yourself with a DWI charge, understanding how Missouri reviews drug impairment may help you make sense of the tests, reports and other evidence in your case. Careful preparation could give you a clearer view of the facts and the issues that may affect the outcome. Together, that understanding and preparation may help you respond to the DWI process with fewer surprises.