Legal Drinking Limit

What is the Legal Drinking Limit?

To be reasonably accurate, there are many factors to consider when determining a driver's legal drinking limit. This includes the period of consumption, rate of consumption and type of liquor consumed must be known along with other critical facts, such as your body weight. However, many people associate the drinking limit with the state’s legal BAC limit. In Washington State the Blood Alcohol Content limit is .08 and for persons under 21 years old the limit is .02. Evidence of a driver’s BAC is gathered by the driver blowing into a breath test machine at the police station known as a Draeger 9510.

Determining if Your Alcohol Consumption Exceeds the Legal Limit to Drive

The Draeger 9510 is highly computerized and uses two different systems to analyze a driver’s breath sample - Infrared Spectroscopy and Electro-Chemical analysis. A driver provides two samples into the machine and since each sample is separately analyzed, there are two test results for each breath sample. The machine rarely produces the same reading for each analysis, so there may be four very different readings on a breath ticket produced from the provided samples. The test results must agree within +/- 10% of the average of the four readings.

However, a DUI defense attorney will know how to use an established scientific method called “Widmark’s Formula” to determine whether the amount you had to drink was, in fact, enough to produce a reading over the legal drinking limit. This evidence is admissible in court to cast doubt upon the results of the breath test machine — ultimately, the jury will decide whether it believes the sworn testimony of citizen witnesses or you are “guilty by machine.”

Washington State Liquor Control Board BAC Charts

In the past, the Washington State Liquor Control Board published and distributed BAC charts for men and women. These charts showed the Liquor Board’s best guess as to what the alcohol level would be for a given amount of drinking.

The Liquor Control Board charts are included here with this caveat: there are so many variables in the formula used to calculate breath test results based upon an individual’s weight and number of drinks consumed that the chart is practically worthless as a method to precisely determine an individual’s breath alcohol concentration. Also, bear in mind also that a person can be charged with DUI even if the breath test reading is under the legal limit, if the arresting officer feels that the ability to drive was impaired by alcohol.

Contact a Dedicated Washington DUI Defense Attorney

If you were charged with a DUI, it’s essential to have a committed DUI defense attorney on your side. A dedicated DUI attorney can help ensure your legal rights are protected at every stage of the DUI process, from arrest to trial. With a focus on developing a tailored strategy in every case, the Fox Law Firm PLLC has been providing high-quality legal services and obtaining favorable results for clients charged with DUIs for 35 years. Contact Attorney Jon Fox for a free consultation by calling (425) 274-9190.