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What’s a DWI Breath test, Blood test, or Urine test?

DWI Tests

What is a DWI Breath Test?

The most common DWI test in Minnesota is a breath test. Sometimes, people will take one breath test at the scene and then be asked to take another at the police station or jail. While both of these tests are breath tests, one is able to be used to prove DWI, while the other is not. The initial test at the scene is called a preliminary breath test (PBT). The statute allows an officer to use the PBT to determine if someone should be arrested for a DWI. However, because this machine is not as accurate as the station test, it is not used to prove that a person’s blood alcohol concentration (BAC) is over the legal limit. That is why officers will ask for a second breath test at the jail or station.

The breath test at the station is used to determine if the person’s BAC is over the legal limit. The statute for this test requires an officer to issue a breath test advisory stating, among other things, that refusing the test is a crime and that the person has the right to contact an attorney. The results of this test can be used to prove that a person’s BAC was over the legal limit, establishing a DWI. This test is susceptible to reliability issues, however. The machine itself needs to maintained and calibrated properly. Often, an officer will run blank samples and a control sample to verify that the readings are within accepted ranges. The person taking the test can also cause skewed results. Certain medical conditions or recent burping or vomiting can skew the results, making them unreliable. An experienced DWI attorney can review the records and determine whether it was conducted in accordance with required procedures.

What is a DWI Blood Test?

Another type of DWI test is a blood test. For this test, an officer must first get a warrant to take a blood sample. A person must also be informed that refusing to submit to the test is a crime. Blood tests are generally accurate samples of a person’s BAC, but it is important that the blood be drawn by a qualified person and stored appropriately so that it remains stable. Issues with the draw or storage can result in the test being thrown out. If a person objects to the blood test, an officer must offer a urine test and vice-versa.

What is a DWI Urine Test?

The third type of approved DWI testing is a urine test. Like a blood test, this test requires a warrant. Urine tests may be reliable, but they can be skewed if a person has not recently urinated before the test. Urine stored in the bladder could reflect a BAC that is not accurate at the time the test is performed. Like a blood test, a person can object to a urine test, but they must then undertake a blood test.

What Defenses are available to DWI Tests?

There are many potential defenses available regarding a flawed DWI test. For example, an officer may lack probable cause to require the test; an officer may give an improper advisory; or the test may not be performed as required. In these circumstances, the test may be thrown out, often resulting in a dismissal of a DWI charge. If you are charged with a DWI and would like to learn about your options for defense, contact experienced DWI lawyer Eric Rice for a free consultation at (651) 998-9660.