Understanding DUI Blood Tests

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 What is a DUI Blood Test?

DUI, or driving under the influence, means operating a motor vehicle while being impaired by the effects of an intoxicant, such as drugs or alcohol. Every state has a version of a DUI statute that prohibits an individual from driving while intoxicated or under the influence of alcohol or drugs.

DUI offenses may also be called by other names, such as:

  • DWI: driving while intoxicated;
  • OUI: operating under the influence; and
  • OMVI: operating a motor vehicle intoxicated.

In some states, there are different types of DUIs based on the intoxicant, such as:

  • Alcohol;
  • Illegal drugs;
  • Prescription drugs; and
  • Over the counter drugs, such as cough syrup.

When an individual is charged with a DUI, a blood test may be used to verify they were intoxicated. In 2016, the Supreme Court of the United States held that it was unconstitutional to bring criminal charges against an individual for refusing to submit to a blood test.

A blood test for DUI takes a sample of the individual’s blood and measures the amount of chemical substance which is present in the blood. Generally, the blood tests are accurate, since they find any traces of any substance the individual has consumed.

Blood tests are not typically given at the scene of the DUI stop or accident, since only qualified individuals may administer the test. In addition, every state has different regulations regarding:

  • Who is qualified to administer the blood tests;
  • How blood tests are taken;
  • How the blood samples are transported; and
  • How the blood tests are analyzed.

Who is Qualified to Administer a Blood Test?

In general, an individual who is under the supervision of a qualified physician, such as a nurse, a physician, or an individual who is licensed in phlebotomy are capable of administering a blood test. A certified law enforcement officer will very rarely be able to draw blood. As noted above, those individuals who are qualified to perform blood tests vary from state to state.

If an individual has a blood test administered on them by an individual who is not qualified to perform the test, then the blood test may be challenged. This is because not following the requirements for a proper blood test collection may provide reasonable doubt regarding the results of the test.

Do Police Need a Warrant to Administer a Blood Test?

In 2016, the United States Supreme Court held that law enforcement is required to obtain a warrant in order to compel an individual to submit to a blood test if they refuse to give consent. It is important to note, however, that this does not apply to breathalyzer tests. No warrant is necessary to administer a breathalyzer test.

In addition, an individual may face criminal charges for refusing to perform a breathalyzer test. The Supreme Court also held that a warrant is not necessary in order to perform a blood test on an individual who is unconscious.

Every state also has implied consent laws which impose penalties on drivers that refuse to submit to a blood alcohol concentration (BAC) test or other chemical testing when law enforcement has probable cause to believe that the individual was operating a vehicle under the influence.

The reason behind implied consent laws is that driving is a privilege. If an individual operates a motor vehicle, they are consenting to being subjected to DUI testing if they are suspected of a DUI. The penalties for not cooperating with DUI testing vary from state to state. However, common penalties include the suspension or revocation of an individual’s driver’s license.

How are Blood Tests Administered?

Prior to a blood test being performed, law enforcement is required to explain the procedure to the individual being tested as well as the penalties for refusing to cooperate with the blood test. Following this, law enforcement will ask the individual to submit to the blood test.

In most cases, a warrant is obtained very quickly in DUI cases in order to preserve the evidence. If an individual refuses to consent or delays in consenting to the blood test, that decision may be treated as a refusal which may result in driver’s license suspension and other DUI penalties.

It is important to note that an individual is permitted to request a different or less intrusive test, such as a breath or urine test. However, if the alternative tests are not available, then the blood test will be administered.

If an individual agrees to submit to the blood test, a qualified individual will clean the arm and use a needle to draw blood. The blood will then be processed. As previously noted, if the blood test is not performed as required, the evidence obtained from the test may be suppressed.

Are DUI Blood Tests Reliable?

A blood test is more reliable than a breathalyzer test because the blood is being analyzed for the exact chemical content and the time of the blood draw. In addition, breathalyzer tests often do not function properly or give inaccurate readings, which requires the test to be administered multiple times in order to verify the results.

There are, however, several reasons why a blood test may be unreliable, including:

  • The blood sample was taken too long after the arrest;
  • The blood sample was contaminated by the alcohol swab that was used before the blood was drawn or
  • The blood sample was otherwise contaminated;
  • The blood sample was not properly stored or transported; or
  • The blood sample was not drawn by an individual who was qualified to administer a blood test.

Can I Challenge the Results of a DUI Blood Test?

As noted above, there are several reasons that provide a basis for an attorney to challenge the legitimacy of a blood test. Challenges may include:

  • The procedure for administering the blood test;
  • The accuracy of the technology that was used to analyze and draw the blood sample; and
  • The testimony of the arresting officer which resulted in the administration of the blood test.

If the court determines that the reason for the blood test was improper or that the correct procedure for administering the test was not followed, then it may be possible for the evidence and results of the blood test to be thrown out, or suppressed. In other words, the results of the blood test could not be used to convict an individual of a DUI.

Should I Hire an Attorney if I Have Issues Involving a DUI Blood Test?

It is essential to hire an experienced DUI attorney if you have any issues regarding a DUI blood test. As discussed above, challenging the administration of or the results from a blood test is often complicated, especially since blood test results are known to be reliable.

If you have been subjected to a blood test and are facing criminal prosecution for a DUI or DWI, it is important to consult with an attorney as soon as possible. Your attorney will only have a certain window of time to challenge the administration or results of the blood test.

Your attorney will also advise you if any defenses are available in your case and represent you during any court appearances. Having an attorney on your side is your best chance at a favorable outcome for your case.


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