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Determining Reasonable Suspicion and Probable Cause

When police officers pull over a driver, there are some commonly recognized driving behaviors they may cite as reasons for further investigation. Depending on the time of day and whether or not it is a holiday, police may be prone to check less common indicators of intoxication. However, once pulled over, an officer uses a fairly standard set of procedures in determining the next course of action, generally based on the driver's on-road behavior.

Contact the Seattle DUI lawyers of the Cowan Kirk Law Firm at 1-866-822-1230 if you are facing DUI charges. Let us put our knowledge of the law to work for you.

Indicators and Rates of Suspicion

The National Highway Traffic Safety Administration issues a basic training chart to help police officers recognize the most common signs of drunk driving. These training materials also assign a percentage figure to inform officers of the probability that the driver in question is intoxicated. Officers may pull over suspected drivers and even arrest them based on these numbers. Some of the following indicators may be used to measure intoxication on the road:

  • Headlights off at night: 30% probability
  • Driving into oncoming traffic: 45% probability
  • Tailgating: 45% probability
  • Drifting between lanes: 50% probability
  • Driving at least 10 miles-per-hour under the speed limit: 50% probability
  • Weaving between lanes: 60% probability
  • Nearly hitting another vehicle or a traffic object: 60% probability

According to these and other qualifying judgments, anything above 25% is considered grounds for reasonable suspicion, allowing police officers to pull over drivers. Anything above 50% is considered probable cause for drunk or drugged driving, allowing police officers to arrest a suspect and conduct further testing.

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If you have been charged with DUI, the consequences can be far-reaching. To learn more about your rights and options as a defendant, contact the Seattle DUI attorneys of the Cowan Kirk Law Firm by calling 1-866-822-1230 today.

Cowan Kirk Kattenhorn

Cowan Kirk is known throughout Washington and the nation for representing all of its clients with commitment, creativity and compassion. We recognize how devastating a DUI charge can be, particularly when our clients learn how incredibly tough Washington's DUI laws have become, even for a first-time offender.

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If you need a DUI defense attorney in Seattle, Bellevue, or King County, contact us today to find out why respect for our clients, a passion for justice, and our commitment to winning have earned each of us the highest honor a member of the bar can receive from our colleagues – their referrals.

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