In Washington, only two types of chemical tests are administered to measure a person's Blood Alcohol Content (B.A.C.) -  breath tests and blood tests.  Unlike some other states, urine analysis is not used in Washington State for DUI purposes.  Breath testing is the most common chemical test, but it is also the most unreliable.  Blood testing is invasive, and only permitted in Washington in very limited circumstances.  Below, you will find a brief overview of the two different types of chemical tests used in Washington State, and the common problems associated with each.

Breath Testing in Washington DUI Cases

If you are arrested for DUI in Washington State, and you were not involved in an accident resulting in death or serious bodily injury to another person, then you will be offered a breath test to measure the alcohol content of your blood.  Only two breath testing machines are approved for use in DUI cases in Washington - the DataMaster and the DataMaster CDM.

The results of a breath test may be the most damaging evidence in any DUI case. Experienced attorneys know that successfully arguing against the test administration and validity could result in suppression of the results. Specific rules and regulations must be followed strictly in the administration of any breath test.  Before a breath sample is taken, the police must advise you of your Miranda rights and your Implied Consent Warnings (which describe the consequences of refusal).  Failure to do so could result in suppression of the breath test or your refusal of it in court.  Additionally, before a breath sample can be obtained, the police must check your mouth and observe you for 15 minutes to ensure nothing is ingested that could skew your results.

Breath tests are the most common chemical test in a Washington DUI case, but they are also the most problematic. They cannot directly measure the amount of alcohol in your blood. Instead, they try to measure the amount of alcohol on your breath, the results of which are then used to estimate the amount of alcohol that might be in your blood.  Most problems with breath tests are a result of improper sample collection, the occurrence of human error, and invalid results obtained on broken machines.  Additional factors that may affect your breath test (resulting in an unreliable and false reading) include regurgitation, radio frequency interference, mouth alcohol, and acetone.

There are two types of breath tests that exist, and depending on your jurisdiction, you may or may not encounter both.  Preliminary Breath Tests are administered on scene to aide the officer in his decision of whether he has enough probable cause to make an arrest. Evidentiary Breath Testing is the more common type of test that is administered at the station (or now in the RV) and it's results are admissible against you in a court of law.

Preliminary Breath Testing:

The preliminary breath test (PBT) is a handheld model used in the field.   They typically have an LCD readout, and lack the ability print the result.  In Washington State, the PBT is not admissible into evidence at trial. This means that the prosecutor and police can not use the results against a person accused of DUI in trial. Furthermore, a suspect usually has an absolute ability to refuse to submit to this test and it can not legally be held against them.

Evidentiary Breath Testing:

Washington uses breath testing Machines called the DataMaster and the DataMaster CDM.  These machines are not portable or handheld like the PBTs, and their results are usually more likely to be admissible against you in a court of law.

The leading manufacturer of Washington State's breath testing instruments is a company called National Patent Analytical Systems, Inc. (NPAS).