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What Is Reasonable Suspicion for a DUI Stop?

Police officers can generally stop motorists only when they have reasonable suspicion of criminal activity. In most states, DUI or sobriety checkpoints remain a controversial exception to the rule. An officer with reasonable suspicion that a crime has occurred can stop and briefly detain a person for a limited investigation. Suppose the officer suspects a motorist of driving under the influence (DUI). In that case, the officer usually carries out a field sobriety test or a blood alcohol content (BAC) test, also known as a Breathalyzer.

This means every arrest for drunk driving begins with an officer's reasonable suspicion that the motorist was involved in criminal activity. Even if a motorist is driving while intoxicated (DWI), a DWI or DUI case can be dismissed if the arresting officer lacked reasonable suspicion for the initial stop.

This article discusses what amounts to reasonable suspicion for a DUI stop. It also addresses the differences between reasonable suspicion and probable cause.

Examples of Reasonable Suspicion for a DUI Stop

Reasonable suspicion that a motorist is impaired can be established by any of the following observations:

  • Straddling the center line
  • An illegal turn or other traffic violation such as running a red light
  • Drifting or swerving from one lane to another
  • Nearly hitting other cars or objects on the roadside
  • Extremely slow or erratic driving
  • Frequent braking
  • Stopping in the middle of the road for no apparent reason

This is by no means a complete list. Anything a law enforcement officer believes is a sign of impaired driving might qualify as reasonable suspicion. Likewise, an officer can investigate further if there's reasonable suspicion that a driver is impaired after making a stop for something entirely unrelated (a burned-out taillight, for example). The smell of alcohol on a driver's breath can provide reasonable suspicion to believe a motorist is under the influence of alcohol.

In some cases, reasonable suspicion for a DUI stop may be established even if the officer didn't witness any actual driving or infraction. For example, an officer can conduct a field sobriety test after a car accident or if a motorist is found unconscious behind the wheel of a parked car. Reasonable suspicion is based on the specific facts of each case.

Reasonable Suspicion vs. Probable Cause

Reasonable suspicion allows an officer to temporarily stop and detain a motorist to investigate further if the officer thinks the motorist may have committed a crime. An officer needs to meet the higher standard of probable cause before making an arrest.

Probable cause means an officer has enough evidence to believe a motorist has probably committed a crime, justifying an arrest. In the context of a DUI stop, an officer likely has probable cause for an arrest if the results of a field sobriety test or breath test point to likely intoxication. The same is true if a blood test shows an illegal blood alcohol content.

Probable cause differs from reasonable suspicion. To meet the probable cause standard, an officer must have enough evidence to suggest that the motorist has most likely committed a crime. Reasonable suspicion, on the other hand, only necessitates that the officer has some indication that the motorist might have committed a crime. It's a fine distinction but an important one.

Did the Officer Have Reasonable Suspicion for Your DUI Stop? Ask an Experienced Lawyer

Whether this is your first DUI arrest or your third, having an initial consultation with a skilled defense attorney can mean the difference between getting the maximum penalty and potentially having your DUI charges reduced or dropped. Do you have questions about the legality of your initial traffic stop or how to handle your criminal charges? Contact a DUI attorney or law office near you. Seeking legal advice from a defense lawyer can help educate you about DUI laws and DUI defenses.

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  • DUI defense attorneys can challenge Breathalyzer/Intoxilyzer or blood test results
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