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DUI Chemical Tests Used in Washington State

Before someone is charged with driving while under the influence of drugs or alcohol (DUI), they typically are subject to one or more DUI chemical tests. These can include, depending on the circumstances:

  • a preliminary breath test
  • a breath test
  • a blood test, or
  • a urine test.

The State of Washington relies on the results of these tests to determine whether or not to charge someone with a DUI. However, there can be problems with these tests. Because of these well-known problems, an experienced DUI defense attorney may be able to successfully challenge these test results.

Preliminary Breath Tests

Often times, the police will rely first on a preliminary breath test, also referred to as a PBT. The PBT, as the name suggests, is a preliminary test. This test is administered on the “roadside.” It is a tool for police to gauge whether someone might have more than 0.08 blood alcohol in their system.

The preliminary breath test does not test for the presence of illegal, prescription, or over-the-counter drugs. It can only inform the police about the possible presence of alcohol. The results of this test are not admissible in court because they are notoriously inaccurate. However, they can inform the police about the value of taking someone down to the police station for additional testing.

Breath Tests

Once someone is taken to the station for additional testing, they may be asked to take a breath test. This test is sometimes referred to as a “breathalyzer” or an “intoxilyzer.” The idea behind this test is that the instrument will measure the amount of alcohol present in a person's body. A person's blood alcohol content (BAC) level is measured by the instrument. However, as recently highlighted in the New York Times and by National Public Radio, there are many problems with these test results. Reports have asserted these tests can be off by as much as 40 percent.

The problems with breath tests are complex. The instrument must be calibrated regularly by someone who knows what they are doing. It must be maintained at a certain temperature. There is an alcohol solution the machine also tests to compare against the breath sample, and this solution must be maintained in a prescribed manner. Any deviation from the required maintenance of the instrument can impact the results. Further, before someone is tested, they must be observed for 20 minutes. If the person vomits or even burps, the wait time must start again because this can detrimentally interfere with the test result.

Blood Tests

A blood test can also measure the amount of alcohol present in the blood. However, like breath tests, there is any number of things that can impact the results.

If the blood is not collected in the proper tube, the blood can ferment and can actually increase the amount of alcohol present in the sample right in the tube. If the person taking the blood first cleans the skin with an alcohol wipe, this can introduce alcohol into the sample. As with breath tests, if the instrument isn't properly calibrated or maintained, this can have an impact on the test results.

Urine Tests

Not surprisingly, there are also problems with urine testing.

First, urine collects in the bladder over time. The amount of alcohol in the urine is reflected by this. Thus, it is important for a person to void the bladder before collecting a sample for testing. This can naturally delay things, and sometimes the police simply choose to collect the first sample, which does not accurately reflect the amount of alcohol present in the person's system.

Next, as with any other test, the instruments used in the testing must be properly maintained to ensure an accurate test result. Of course, the urine sample must also be stored correctly in order to rely on the results.

Interpretation Errors

When testing for the presence of drugs or alcohol in blood and urine, once the test is complete, even assuming the instruments and the sample were properly maintained, the results must be interpreted. If the person reviewing the sample isn't properly trained, or, frankly, isn't giving their job the time and attention it deserves, they may misread the results.

Challenging DUI Chemical Tests

In every DUI case, the test results should be carefully examined by someone experienced in reviewing these results. Attorney Vinny Randhawa represents people charged with DUI in King County, Pierce County, and Snohomish County, Seattle, Washington. Call (425) 228-2202 to talk to him about your case today.

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Attorney at Law Vinny Randhawa
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