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Drunk Driving Patterns In Washington State

Washington State law enforcement officers are trained to look for specific driving patterns that are associated with DUI (Driving Under the Influence of Intoxicants).

All Washington State troopers and local law enforcement officers receive very similar training with regard to identifying potential drunk drivers.  Over the years, we have often been asked what causes certain drivers to get pulled over for suspicion of DUI?  As detailed below, many factors can contribute to getting pulled over for suspicion of DUI.  Two of the most important ones, however, are simply the day and time of your driving.

It's no coincidence that law enforcement agencies put out special "emphasis patrols" during periods when they suspect more drunk drivers will be on the road.  These are typically on Thursday, Friday and Saturday nights from the early evening until the early hours of the next morning.  Many holidays such as the Memorial Day, the Fourth of July, Halloween and New Year's Eve also have special emphasis patrols out in force. 

The same is true for major events such as the Super Bowl, Seahawks games (especially playoff games), local rock concerts and various festivals.  During and after these events especially, the police are looking for specific driving patterns that they believe indicate impairment.  Whether these patterns are actually a reliable indicator of impairment, however, remains an issue of great debate, particularly among experienced DUI lawyers.

What driving patterns make the police suspect a driver may be drunk?

For the most part, the evidence that these driving pattern indicate that person is DUI come from the National Highway Transportation Safety Administration (NHTSA).  NHTSA has identified the 20 most common "driving symptoms" allegedly exhibited by drunk drivers.  In its DUI training materials, which have been universally adopted by law enforcement agencies throughout Washington State, NHTSA offers a statistical probability the driver is under the influence based on the observed "driving symptom".

Furthermore, NHTSA claims that when multiple symptoms are observed, it is appropriate to add 10% to the highest valued symptom.  For example, if the person exhibits drifting (50%), erratic braking (45%), and swerving (55%), then probability that he is DUI is 65%.

DUI Driving Symptoms:
  • 65%    Turning with a wide radius
  • 65%    Straddling center or lane marker
  • 60%    Appearing to be drunk
  • 60%    Almost striking an object or vehicle
  • 60%    Weaving
  • 55%    Driving outside the designated roadway
  • 55%    Swerving
  • 50%    Slow speed (more than 10 mph below the speed limit)
  • 50%    Stopping in traffic (without a reason)
  • 50%    Drifting
  • 45%    Following too closely (tailgating)
  • 45%    Driving with tires on center or lane marker
  • 45%    Erratic braking
  • 45%    Driving into opposing traffic
  • 40%    Signaling inconsistently with driving actions
  • 35%    Stopping inappropriately (other than in lane)
  • 35%    Turning abruptly or illegally
  • 30%    Accelerating or decelerating suddenly
  • 30%    Headlights off after dark
What is very interesting about this list is what it is missing:  Speeding.  Many of our DUI clients are initially pulled over for speeding.  And, over the years, we have heard many officers try and claim that speeding is an indication that a driver may be drunk.  In all of our years, however, we have never seen one study that showed a significant correlation between speeding and driving under the influence. 

Our attorneys attend multiple DUI training sessions every year, and we have never once seen any evidence suggesting that speeding indicates that the driver is driving drunk.  Indeed, just the opposite.  The studies all show that there is no significant relationship between DUI and driving in excess of the speed limit.  A speeding driver is no more likely to be drunk than sober.  This is also borne out by our own personal observations over the years.  Our offices handle hundreds of speeding and traffic tickets in Washington State every year.  The overwhelming majority of speeding tickets are issued without any indication of DUI.

What does an officer look for after pulling over a suspected drunk driver?

Upon initiating a traffic stop on someone that they suspect has been driving under the influence, the officer is trained to look for certain clues or signs that are supposed to assist in ascertaining whether or not the driver is intoxicated.  Alcohol is a central nervous system depressant and has many affects on the human body.  As with all substances, however, the affects will vary wildly depending the individual's tolerance, weight, sex, and physical fitness.  The affects will also differ greatly depending on how much alcohol was consumed, whether the person had eaten anything prior to or while drinking, as well as on many other critical factors.

Here are some of the clues that law enforcement are trained to look for as signs of impairment or intoxication:


    Odor of alcohol on breath or person

    Bloodshot and/or watery eyes
    Flushed face
    Slurred speech
    Speaking incoherently
    Slow verbal responses
    Poor motor skills (difficulty retrieving one's driver's license, registration and proof of insurance)
    Unsteady on their feet (including circular sway while standing)
    Displaying balance and coordination problems (staggering, falling, or leaning)
    Unable to understand and follow simple direction
    Unable to keep their story straight, often giving different answers to the same or similar questions
    Difficulty getting out of the motor vehicle (or using the vehicle for balance)
    Unaware of the volume of their voice (speaking too softly or loudly)
The simple truth, however, is that there are a myriad of reasons why an individual might exhibit one or more of these signs even though they are not intoxicated.  To law enforcement, however, this matters not.  Most officers will make no inquiry as to other possible reasons a person might be exhibiting these signs.  And, even though an individual might portray any number of these signs for reasons not involving alcohol consumption, the officer will invariably use the signs against the driver and make a DUI arrest.  This is especially true when the officer sits down to write his report.