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Charles H. Williams,
Attorney and Counselor
at Law, P.S.
707 South Snoqualmie
Suite 4A
Seattle, WA 98108

Toll free:800-854-3458
Seattle Law Office Map


Seattle DUI Breath Test Lawyer

A variety of factors can cause breath and blood tests to be inaccurate or inadmissible. If you are facing DUI charges, a qualified attorney can protect your rights by determining if a police officer failed to follow proper procedure when administering a breath or blood test, or if any of the information received from testing is potentially inaccurate.

At the law office of Charles H. Williams, Attorney and Counselor at Law, P.S., we defend individuals living in and around Seattle and other parts of western Washington who are facing DUI charges.

A Lawyer With the Knowledge and Ability to Protect Your Rights

With more than 30 years of legal experience, attorney Charles Williams has handled many hundreds of DUI cases and has the knowledge and ability to conduct a thorough investigation and determine what facts and arguments would be most effective in defending you. He delivers personalized service to his clients. He will answer your questions, address your concerns, and provide you with all the information you need to decide how to proceed with your case.

To speak with an attorney contact the firm online or by calling 206-707-8524 or 800-854-3458.

Challenging Breath Test or Blood Draw

A breath test result obtained through use of a portable breath test device at the scene of an arrest is not admissible at trial. The use of portable devices (such as Breathalyzers), is limited to establishing a basis for arrest. Only the breath test result obtained from the BAC DataMaster machine at a police station can be used at trial.

The admissibility of the DataMaster test results, however, is itself subject to challenge. The police officer conducting the breath test may employ improper procedures, or other factors may be cause an inaccurate result, including:

  • Failure to quantify uncertainty of the alcohol-concentration measurement;
  • DataMaster errors related to improper operation, premature sampling, mouth alcohol, interferants, and manner of breathing; and
  • Defendant's physical condition, including body size, body temperature, low-carb diet, dentures, diseases such as diabetes, etc.

Blood draws to test for alcohol concentration are not authorized in Washington except in certain very limited circumstances (RCW 46.20.308), unless made pursuant to a search warrant issued by a court.

The admissibility of the blood test result is also subject to challenge. Factors that can lead to an inaccurate blood test result include:

  • Failure to ensure the blood draw is conducted properly by a qualified person;
  • Failure to follow the prescribed methodology when testing samples; and
  • Failure to take IV infusion into account.

Refusal to Take Breath Test

Many defendants refuse to take breath tests, even though they are warned that their refusal to submit to the test can be used against them in a criminal trial. There the fact of refusal is admissible as circumstantial evidence of the driver's consciousness of his or her guilt.

Arguably, this inference begs the question of guilt, because it assumes that the driver believes the very fact to be proven at trial — that his or her ability to drive was lessened to an appreciable degree. But the driver may have other reasons for refusal — e.g.:

  • The driver may believe in good-faith that breath test technology in Washington is unreliable, based on numerous media reports over the years;
  • The driver may mistrust the officer administering the test based upon the latter's behavior during the encounter;
  • The driver may simply be following the recommendation of legal counsel.

Often the fact of refusal can be suppressed by a court prior to trial or simply discounted by jurors during trial when it can be shown that the apparent refusal was caused by:

  • The officer's failure to address any confusion by the driver;
  • the officer's giving misleading or inaccurate information or advice to the driver;
  • The officer improperly registering an incomplete test as a refusal; or
  • The driver's inability to complete the test despite earnest attempt because of a medical condition.

Contact a Bellevue Blood Test Attorney Today

To determine if mistakes were made during your breath or blood alcohol test, contact a Seattle DUI breath test attorney with the experience to find the best arguments to fight your case.

Contact the law office of Charles H. Williams online or by calling 206-707-8524 or 800-854-3458.

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