Can a Breath or Blood Test Be Challenged?

Can a breath test be challenged? Yes, but only if the defense attorney is intimately familiar with DUI laws, the physiology of breath testing, and the intricacies of the police procedures used in administering breath tests and maintaining the breath testing machines. For over 30 years, the only breath testing machine used for residential purposes here in Washington state is the BAC DataMaster. I wrote the chapter in our book, Defending DUIs in Washington, on this breath testing machine. Now there is a new machine in some areas of Washington state. It is called the Draeger Alcotest. Although this machine was only recently (November, 2014) introduced into police station in the state of Washington, I have been studying this machine and Washington’s development of it for the last three years. It is important for a defense lawyer to always be well informed about the technology that will be used in court as evidence against one charged with DUI.

Most people think that the breath and blood testing machines used by the state are automatically accurate, but this not always true. In analyzing your case, your defense attorney must investigate the test result to determine how it may be challenged in court. A breath or blood test must meet specific legal and scientific standards if it is to be considered reliable enough for use in court as evidence. If these standards are not met, the jury may disregard the test results or a judge may decide that the test results should be suppressed, that is, not be considered at all. These rules prevent innocent persons from being wrongfuly convicted by inaccurate evidence.

The law and science each provide valid challenges to DUI test results, and the lawyer defending a DUI case must be knowledgeable in both. Records may be subpoenaed which contain information about the breath test that is not always documented on the breath ticket given to the defendant after the breath test. These records may for the basis of a court challenge to the procedures used in administering the breath test, and thus the legality of the test itself.

A person under arrest for DUI must be “warned” of the consequences of taking or refusing the breath test. The procedures used to administer this Implied Consent Warning are critical since a significant deviation from a proper advisement means that the breath test should not be admitted into evidence. Also, a breath test must not be used in court unless the defendant was advised of the right to talk to a lawyer before being asked to take the test. There are many potential legal challenges to a breath test not listed here but which will be considered by a good DUI attorney when defending your case.

Even when the breath test is allowed into evidence, there are valid challenges to its accuracy which may be considered by the judge or jury. These are based upon test procedures and also inherent problems in the technology of the breath testing machine itself. The law permits the judge or jury to totally disregard breath or blood test results when not completely convinced that the results are accurate.

The law also gives you the right to get your own private test which may be used to challenge the breath or blood test you took while in police custody. In most cases this additional test will be a blood test taken at your own expense at a hospital emergency room. Since this is a good way to challenge the police test results, courts have ruled that the police cannot intentionally prevent you from obtaining your own independent test, should you choose to do so.

A breath test can be discredited by the live testimony of independant witness who can verify how much alcohol the you actually had to drink. Using well accepted scientific principles, your actual blood or breath alcohol may be calculated from the information the witnesses supply. A judge or jury is entitled to disregard the police breath or blood test results if the testimony of the defense witnesses is deemed credible.

A good defense attorney will know of experts in the field of breath testing and physiology who may be able to present persuasive testimony challenging the accuracy and reliability of the breath test. A good working relationship between the defense attorney and such experts can enhance the ability to challenge breath or blood tests in a meaningful and credible way in court.

We have discussed only a few of the many ways in which a breath or blood test may be challenged in court. Your first step should always be to consult with an experienced attorney to discuss the facts of any particular case.