How Does the Impairment Definition for a DUI Compare to the BAC Standard?

How Does the Impairment Definition for a DUI Compare to the BAC Standard?Many Washington drivers are under the mistaken impression that they can only be charged with driving under the influence if their blood alcohol content (BAC) level is .08 or higher. That assumption is false. The BAC test is just one test. The police can also stop you and charge you if your driving is impaired due to alcohol, no matter the amount in your body. Many drivers have a low tolerance level for alcohol. For some drivers, just one beer or one glass of wine can cause the drinker to be unable to control his/her vehicle.

Washington State’s Driving Under the Influence statute has the following provisions:

A driver can be found guilty of driving under the influence of intoxicating liquor, marijuana, or any drug if they drive a vehicle in Washington and any of the following conditions apply:

  • The driver has, within two hours after driving a BAC result of .08 or higher – as determined by a proper analysis of their breath or blood.
  • The driver has, within two hours after driving, a THC concentration of 5.00 or higher – as determined by a proper blood test.
  • The driver is “under the influence of or affected by intoxicating liquor, marijuana, or any drug”
  • The driver is “under the combined influence of or affected by intoxicating liquor, marijuana, and any drug.”

It is not a defense that the driver is entitled to use the drug under Washington laws. Drivers who take approved drugs must still be in control of their vehicles. If they are not in control, they can be charged with a DUI.

Drivers facing DUI charges have an affirmative defense to this violation – that they consumed alcohol or drugs with THC between the time they were stopped and the time of the chemical test – if they timely advise the prosecution they want to assert the defense. The defendant must prove his/her position by a preponderance of the evidence.

In Washington, the analysis of the breath or blood samples obtained more than two hours after the person was alleged to be driving – may be used as evidence that “within two hours of the alleged driving, a person had an alcohol concentration of 0.08 or more.” The analysis can also be used as evidence to show “an alcohol concentration above 0.00” “that a person was under the influence of or affected by intoxicating liquor or any drug in violation” of the statute.

A DUI conviction, even if your BAC was less than .08, can result in a gross misdemeanor or a Class B felony charge depending on certain conditions; such as your prior DUI record within the prior 10 years, whether anyone was seriously hurt or killed, and whether a juvenile was involved.

The Bellingham Herald explained in a recent article that the BAC .08 limit is a “per se” limit. This means if your breath test or blood test shows that your BAC was .08 or more, then there’s no need to introduce any other evidence to show you were driving while impaired. If your BAC is below .08, the arresting officer needs to introduce additional evidence.

What evidence of impairment can be introduced in addition to BAC level?

The prosecution can introduce the following evidence of impairment:

  • How you performed on the three standard field sobriety tests. Police officers in Vancouver and Battle Ground routinely ask drivers they suspect were driving under the influence of alcohol to perform these tests.
    • Horizontal Gaze Nystagmus. Here, the driver suspected of driving while intoxicated will be asked to follow an object (such as a pen) with their eyes so the officer can examine the driver’s eye movements.
    • Walk-and-Turn. This test requires that the driver walk heel-to-toe in a straight line. The officer is checking to see if you can follow directions and that you can physically pass the test.
    • One-Leg-Stand. Here, the driver will need to be able to stand on one leg for a specific period, such as 20 seconds.
  • Observations of how you were driving. For example, an officer can state that you were speeding, swerving in and out of lanes, failed to use your turn signals, tailgated, or that you committed other traffic violations or irregularities.
  • Observations of your physical condition. For example, an officer can state you had alcohol on your breath and that your eyes were bloodshot. The officer can add that your speech was slurred or other observations of impairment.
  • Observations that you had alcohol in your car. Officers can normally search your car without a warrant if they suspect you of drunk driving (though our lawyers will normally contest the search). If a legal search shows that you had a container of beer or other alcohol and that the container was open, that evidence can be introduced to show you were driving while impaired.

There are other BAC limits that automatically mean a driver is impaired in Vancouver and Battle Ground.

  • Commercial drivers can be charged with a DUI if their BAC is .04 or more.
  • Minors can be charged with a DUI if their BAC is .02 or more.

What are the physical effects of alcohol?

How much a drink affects your driving varies, depending on the type of drink, your weight, your gender, genetics, and other factors.

According to American Addiction Centers, impairment symptoms based on BAC level are:

  • 02%: “You will feel relaxed, experience altered mood, feel a little warmer, and may make poor judgments.”
  • 05%: At this BAC level, you make talk louder and gesture more. You may lose some control of your muscles such as the ability to focus your eyes. Your judgment starts to become impaired. Following objects becomes harder. Your ability to respond to emergencies, such as traffic emergencies, becomes more difficult.
  • 08%: This is the “per se” impairment level in every state except for Utah. At this level, drivers lose their coordination. Your speech, reaction time, balance, and hearing become worse. “Reasoning, judgment, self-control, concentration, and memory will be impaired.”
  • 10%: At this level, driver reaction time and control are much less than they should be. Speech becomes slurred. Reasoning and coordination are poor.

At Philbrook Law Office, our Vancouver and Battle Ground, WA DUI defense lawyers assert every possible defense available. We often seek to suppress the evidence against you, such as challenging the validity of field sobriety, breath, and blood tests. We work to obtain dismissals and acquittals. We also work to obtain plea agreements that reduce the charges to less serious offenses. To assert all your defenses, call our offices in Vancouver or Battle Ground, WA at 360-695-3309 or fill out our contact form to schedule an appointment.