What tests might occur during a DUI or DWI stop?


Law enforcement may request field sobriety testing during a traffic stop if they suspect a driver of being under the influence (DUI) or driving while intoxicated (DWI). What tests can police ask for, and what are drivers' rights surrounding them? Keep this information in mind as you get behind the wheel.

Field Sobriety Testing
Field sobriety tests, which are controversial in some circles, are voluntary, but refusal may come with consequences. Jurisdictions nationwide can employ the NHTSA's Standardized Field Sobriety Test, which includes three individual tests: the one-leg stand, the walk-and-turn and the horizontal gaze nystagmus (HGN) test (otherwise known as following an object from side to side with the eyes). 

Police use these tests to determine probable cause for arrest. If law enforcement determines they have evidence that a driver is impaired, they may not feel the need to interrogate. In this case, the Miranda warning does not have to be read. 

No-Refusal Situations
An increasing number of law enforcement agencies are implementing no-refusal periods or checkpoints. In these jurisdictions, when an individual suspected of drunk or impaired driving refuses to submit to a Breathalyzer or field sobriety test, a search warrant is requested for a blood or urine sample. If a judge signs off on the search warrant, the driver must submit to the testing or risk prosecution.

Drugs and Driving
Driving under the influence of legally prescribed medications can also lead to an arrest. Some law enforcement agencies across the U.S. rely on drug recognition experts to assist with these particular DUI cases.

In states that have legalized marijuana, including Colorado, police are researching ways to best test for drug usage. A device that determines whether a driver has tetrahydrocannabinol (THC) in his or her system is a possibility.