What is the Legal Drinking Limit in Washington?

Driving under the influence of alcohol is a serious offense in Washington that can lead to serious ramifications, including jail time, monetary fines, license suspension, and reputational damage. While a first conviction can come with steep penalties, a repeat offender can face even stiffer consequences. Like other jurisdictions across the country, Washington imposes strict blood alcohol concentration (BAC) limits on drivers. But it’s crucial to keep in mind that there are various factors that can impact an individual driver’s legal drinking limit, apart from the number of drinks consumed.

What is the Legal BAC in Washington?

The amount of alcohol in a driver’s system directly affects their coordination and ability to operate a vehicle. But there is no specific number of drinks when it comes to a driver’s legal drinking limit — their level of impairment is determined by their BAC. In Washington, there are different BAC thresholds for operating a vehicle, which depend upon the class of vehicle and the driver’s age. Notably, a person can be charged with DUI even if a breath test reading was under the legal limit, if the arresting officer had reason to believe that the ability to drive was impaired by alcohol.

The BAC limits in Washington are as follows:

• Underage drivers — Drivers who are younger than 21 have a BAC limit of .02% under Washington law. Those who have been caught driving with a BAC at this amount or higher can be charged with “Minor Driving After Consuming Alcohol,” commonly known as an underage DUI.
• Non-commercial drivers — Regular motorists operating non-commercial vehicles, such as passenger cars and SUVs have a BAC limit of .08%. Drivers who have been caught behind the wheel with a BAC at this level or higher can be charged with a DUI.
• Commercial drivers — Operating a commercial vehicle comes with a significant amount of responsibility and different legal standards apply to them. A .04% BAC results in revocation of the CDL for those who operate commercial vehicles such as buses, tractor-trailers, tow-trucks, and transport hazardous materials.

People often make the mistake of trying to determine whether they’ve reached the legal drinking limit based on the number of drinks they’ve consumed or how they feel. However, there are many variables to consider when it comes to determining a driver’s BAC, including their body weight, the period of consumption, and the rate of consumption. Other factors can include whether the driver was taking medications and had food in their stomach at the time the alcohol was consumed. Unlike many people might believe, having a high tolerance level for alcohol does not impact a person’s BAC.

There is no way for a driver to quickly reduce their BAC level — it begins to decrease following consumption of the last drink as the body metabolizes it. While about 90% of alcohol is metabolized, the remaining alcohol leaves the body through perspiration, breath, and urine.

How is a Driver’s BAC Determined?

There are several ways law enforcement can test a driver’s BAC to determine whether they’ve exceeded the legal drinking limit to drive. For example, the police may use a breathalyzer, draw blood for laboratory analysis pursuant to a search warrant. Specifically, the Draeger 9510 is the machine that is used to analyze a driver’s breath sample for court purposes. This device is highly computerized and uses two different systems — the Infrared Spectroscopy and Electro-Chemical analysis.

When the Draeger 9510 is used, a driver provides two breath samples for the machine. While each sample is separately analyzed, two test results are returned for each sample provided. The machine rarely produces the same reading for each analysis, and there may be four very different readings on a breath ticket produced from the samples. The test results must agree within +/- 10% of the average of the four readings to be used in court.

The results provided by the Draeger 9510 are generally admissible in court. However, these tests are often flawed — if the test or machine was faulty in some way, a knowledgeable DUI defense attorney may be able to challenge the results. Not only must the machine have been properly calibrated and maintained, but the police officer must have been trained and certified to operate it.

A DUI defense attorney will also know how to use an established scientific method called “Widmark’s Formula” to dispute the machine’s reading. This equation can be used to determine whether the amount a driver had to drink was, in fact, enough to produce a reading over the legal drinking limit. Ultimately, “Widmark’s Formula” can be used to cast doubt upon the results of the breath test machine at trial.

Contact an Experienced Washington DUI Attorney

If you have been accused of exceeding the legal drinking limit and driving, it’s vital to have a DUI defense attorney by your side who can fight the charges against you. Providing dedicated representation and skillful advocacy, the Fox Law Firm PLLC has been assisting clients throughout Washington with a wide variety of DUI matters since 1985. Contact Jon Fox for a complimentary consultation to learn how he can help by calling (425) 584-6649.