When facing a DUI charge in Washington State, one of the most critical pieces of evidence against you will be the results of a chemical test. Law enforcement primarily relies on two types of tests to measure blood alcohol concentration (BAC): breathalyzers and blood tests. Each has its own advantages, weaknesses, and legal implications. Understanding the differences between these tests and how they can be challenged in court is essential for anyone accused of driving under the influence.

Breathalyzer Tests: The Most Common DUI Test

In Washington State, most DUI cases involve a breathalyzer test. Law enforcement officers use this device because it provides quick and non-invasive results. The breathalyzer measures the alcohol content in a person’s breath and then estimates their BAC. If the BAC exceeds the legal limit—0.08% for adults, 0.04% for commercial drivers, and 0.02% for drivers under 21—the driver will likely be arrested and charged with DUI.

The most commonly used breathalyzer in Washington is the Dräger Alcotest 9510. This machine is stationed at police departments and testing facilities and is considered more reliable than portable breathalyzers used during roadside stops. However, despite its widespread use, breath tests are not always accurate and can be challenged in court.

Problems with Breathalyzer Accuracy

Breathalyzers, while convenient for law enforcement, are prone to errors. The machine must be properly maintained, regularly calibrated, and administered correctly by officers. Any deviation from standard procedures can result in inaccurate readings.

One common issue is residual mouth alcohol, which can be left behind from recent drinking, mouthwash, or even certain medical conditions like acid reflux (GERD). If a driver has burped or vomited before the test, the breathalyzer may detect alcohol from the mouth rather than the lungs, leading to an inflated BAC reading.

Medical conditions can also impact breath test results. Diabetics, for example, can produce acetone in their breath, which some machines may misinterpret as alcohol. Additionally, individuals on low-carb or keto diets may have elevated levels of ketones, which can create a false positive reading.

Another potential defense against breathalyzer results is improper administration. Washington law requires officers to observe the suspect for at least 15 minutes before administering a breath test to ensure no contamination occurs. If an officer fails to follow this procedure, the test results may be invalid.

Blood Tests: The More Accurate, But Invasive, Option

Unlike breath tests, which estimate BAC, blood tests directly measure the alcohol or drug content in a person’s bloodstream. Because of their accuracy, blood tests are often considered the gold standard for DUI cases. However, they require a trained medical professional to draw the blood, and the sample must be properly handled and analyzed.

Blood tests are usually conducted in DUI cases where drugs are suspected or when a driver refuses a breath test. They are also used in cases involving serious accidents, injuries, or fatalities. Since breathalyzers only measure alcohol, a blood test is necessary if an officer suspects impairment from marijuana, prescription medication, or other substances.

Can Blood Tests Be Challenged in Court?

Although blood tests are more accurate than breathalyzers, they are not immune to errors. For a blood test to be legally admissible, law enforcement must follow strict protocols. If there is any break in the chain of custody, meaning the sample was not properly documented and handled from collection to analysis, the results may be challenged in court.

Another potential issue with blood tests is contamination. If the sample is not stored at the correct temperature or is exposed to bacteria, it can ferment and produce alcohol, leading to an inaccurately high BAC reading. Additionally, if there is a delay between the time of arrest and when the blood is drawn, the BAC may change, meaning the test may not reflect the driver’s true level of impairment at the time they were driving.

Can You Refuse a Breathalyzer or Blood Test in Washington?

Under Washington’s implied consent law, drivers automatically agree to submit to a breath or blood test if they are arrested for DUI. Refusing to take a breathalyzer test comes with serious consequences, including a one-year driver’s license suspension for a first offense. The refusal can also be used as evidence against the driver in court, potentially making it more difficult to defend against DUI charges.

Blood tests, however, typically require a warrant unless there are exigent circumstances, such as an unconscious driver in a hospital after a crash. If a driver refuses a blood test and law enforcement obtains a warrant, the test can still be conducted against their will, and the refusal may still lead to additional penalties.

Which Test is Better for Your Case?

Both breathalyzer and blood test results can be used as evidence in DUI cases, but they are not infallible. Breath tests are more common and easier to administer but are also easier to challenge due to their potential for human error and machine malfunctions. Blood tests are more precise but require strict procedures that, if not followed correctly, can render the results inadmissible.

If you have been charged with DUI, your defense strategy will depend on the type of test used and the circumstances surrounding it. A skilled DUI attorney can review the evidence, identify weaknesses in the testing process, and build a strong defense on your behalf.

Fight Your DUI Charge with the Law Office of Erin Bradley McAleer

A DUI conviction can have severe consequences, including license suspension, hefty fines, and even jail time. If you have been arrested for DUI in Washington, it is crucial to have an experienced attorney on your side. At the Law Office of Erin Bradley McAleer, we have successfully defended countless clients against DUI charges by challenging the accuracy of Breathalyzers and blood tests.

Contact us today for a free consultation and let us fight to protect your rights, your license, and your future.