Introduction to United States Supreme Court Rules Warrantless Blood Tests for DUI Detection are Unconstitutional

Drinking and driving laws require accurate detection of blood alcohol concentration in every driver that law enforcement believes may be impaired while driving. Some methods that are commonly used include: field sobriety tests, breathalyzer tests, and blood tests. Each method of detection is fairly common, but the United States Supreme Court recently ruled that warrantless blood tests for DUI detection are deemed to be unconstitutional.i

Why is DUI Detection So Important?

When it comes to drinking and driving, the key to determine whether or not a driver is impaired beyond the point that is legally permitted, law enforcement needs to accurately be able to detect the blood alcohol concentration of the individual. So, to begin with, what is blood alcohol concentration and why is it used to detect if a person is impaired? Blood alcohol concentration is the percentage of ethanol in the person’s blood and is calculated based on an equation.ii Based on the amount of alcohol in the persons system, the equation is used to determine whether that person is past the legal limit – which is 0.08%. Every ounce of alcohol in a person’s body will have an affect, but saturating the body with too much alcohol can cause a person to become seriously impaired. The law recognizes that a person may be intoxicated up to 0.08% before they are considered too impaired to operate a motor vehicle. Today, this is standard in all fifty states.iii

Now, 0.08% blood alcohol concentration is a very specific number, and it is possible to have that number skewed if detection methods are improperly administered. The difference between a 0.07% blood alcohol concentration and a 0.08% blood alcohol concentration could be thousands of dollars and even jail time for the individual. For this reason, the legal system seeks to have the most efficient methods for detection of blood alcohol concentration. Arguably, the blood test is the most accurate way of detecting the blood alcohol concentration in the suspected individual.iv This makes sense considering the basis of whether or not a person is legally impaired is based on what the individual’s blood alcohol concentration is.

The use of Blood Tests to Detect Blood Alcohol Concentration

The use of blood tests to detect blood alcohol concentration has been a common practice for many years, but recently the United States Supreme Court has decided that it needs more restrictions put in place.v This ruling just took place this summer, so prior to that, the use of a blood test to detect blood alcohol concentration was a common practice, even roadside blood tests are commonly administered. Many states, like Arizona and California, have what is called the implied consent to blood, urine, or breath tests if the driver has been pulled over and is suspected of being impaired.vi The law in these states says that if you are lawfully arrested by an office who has reasonable grounds to believe that you have been drinking and driving under the influence of alcohol or drugs, then you have impliedly consented to taking a chemical test of your blood, breath, or urine, to determine your blood alcohol content.vii The test of choice must be administered within two hours of the driver being pulled over.viii Up until this summer and the changes to the law with blood tests for DUI detection, the officer who pulled the impaired driver over was able to choose which test to administer.ix If the driver refuses the test after being arrested, the police officer will require the driver to surrender their driver’s license and will file a report to suspend that driver’s license.x

Now, if the driver does consent and the blood is drawn for alcohol content detection, it is not as fast at detection as the breathalyzer – but it is more accurate. Even though the blood is not analyzed immediately after being drawn, the blood in the sample will remain at the same alcohol concentration as when it was drawn – unless there is some error along the way.xi To begin the process properly, the blood must be collected in a manner that does not affect the integrity of the sample.xii Even though it seems like drawing blood should be simple, there are ways to mess up the process. In fact, studies have shown that there is an error rate of up to 50% when it comes to drawing blood for DUI detection.xiii This is one way in which the driver may be able to get out of charges, so it is important that the blood is drawn properly. Doing warrantless blood tests for DUI may entail carelessness.

Next, the blood has to be properly stored. If the blood sample is not stored properly, i.e. the blood is left out on the counter rather than in the cooled storage, the composition of the blood may be affected, which can lead to inaccurate results.xiv Since the blood will likely not be tested immediately after it is collected, making sure it is stored properly will ensure accurate results. Finally, the actual testing of the sample needs to be done properly. The equipment used has to be cleaned regularly, and maintained.xv So even though the process of detecting what the alcohol concentration is in a blood sample is very common, the technician completing the job needs to be careful every step of the way. One mistake could lead to a person’s charges being dismissed even though he was guilty of drinking and driving. Doing warrantless blood tests for DUI does not provide accountability.

Why Warrantless Blood Tests for DUI were deemed Unconstitutional?

warrantless blood tests for dui are unconstitutionalNow, considering that the blood test is the most accurate way to detect the alcohol concentration in a person’s blood – why did the court determine that this could not be done roadside without a warrant? Up until this ruling, if the state had the implied consent rule as discussed above, the officer could chose to have the blood test performed against the drivers wishes.xvi If the driver refused, the officer could suspend the driver’s license and have the driver face other consequences.xvii The United States Supreme Court decided that this was just too invasive and was a violation of privacy of the driver.xviiiThe Supreme Court pointed out that there are other methods of detection that are less intrusive than the blood test, and because of that the driver has of an expectation of privacy.xix For example, the breathalyzer test. This test has the driver blow into a device and the device can detect the amount of alcohol in their system.xx As the Supreme Court puts it, there is no real expectation of privacy when it comes to the air in a person’s lungs.xxi There is however an expectation of privacy when it comes to a persons blood.xxii A person blood provides much more information than just what the alcohol concentration is at that time. A blood test provides the individuals DNA, and if a blood test to determine the alcohol concentration is given – the government now has that information against the will of the individual. This is especially concerning if the individual who has their blood taken was not guilty of impaired driving. There is no way to get back that information.

Another reason that the Supreme Court provides for why a blood test requires either consent of the individual or a warrant is how intrusive the blood test is.xxiii A blood test requires the skin of the individual to be punctured in order for the technician to reach the veins to collect the blood sample.xxiv As many people know, trying to draw blood is not always successful on the first try – so the individual could have multiple puncture wounds on their arm and even have bruising afterwards. Doing warrantless blood tests for DUI intrudes illegally. If the individual is asked to take a breathalyzer test, none of these risks will arise.

Now, time is a concern when it comes to the blood test, and receiving a warrant before performing a blood test may not always happen quickly enough. The longer it takes to draw blood from the individual, the lower the blood alcohol content will be. The body metabolizes alcohol at a constant rate after consumption, so every minute the police office has to wait could mean the difference between the driver being impaired beyond the legal limit and the driver being impaired below the legal limit. This could also be the difference between a standard DUI, which is 0.08% blood alcohol concentration and an extreme DUI, which is 0.15% blood alcohol concentration. The Supreme Court has always found that individual’s liberties take precedent over everything else. So, if the police officer cannot obtain a warrant within an appropriate time frame to obtain an accurate blood sample – then the police officer should probably just use a breathalyzer test or other means of detection. It is better to use an alternate route, than it is to stomp on the rights of the United States citizens by doing warrantless blood tests for DUI.

Conclusion to United States Supreme Court Rules Warrantless Blood Tests for DUI Detection are Unconstitutional

This ruling has a large impact on the states, like Arizona and California, who have laws that state there is informed consent to a blood test if the person has been pulled over for drinking and driving. In essence – there no longer is implied consent. The driver must consent at the scene of the crime, or the officer must receive a warrant to perform the test. This is true even if the driver is brought down to the station. If the driver says no to a blood test, no matter where they are, the officer has to abide by that if no warrant is available. They cannot do warrantless blood tests for DUI.


i See Supreme Court Says Warrantless Blood Draws in DUI Arrests are Unconstitutional ABA Journal (Published June 23, 2016) http://www.abajournal.com/news/article/supreme_court_says_warrantless_blood_tests_incident_to_drunken_driving_arre

ii See Blood Alcohol Content Wikipedia (Accessed July 1, 2016) https://en.wikipedia.org/wiki/Blood_alcohol_content

iii See Blood Alcohol Level Chart / Are you Legally Drunk / BAC Level NOLO Legal Encyclopedia Driving Laws (Accessed July 1, 2016)

iv See DUI and DWI Tests for Alcohol or Drugs: Are they Accurate? NOLO Legal Encyclopedia (Accessed July 1, 2016) http://www.nolo.com/legal-encyclopedia/dui-dwi-tests-alcohol-or-30317.html

v See Supreme Court Says Warrantless Blood Draws in DUI Arrests are Unconstitutional ABA Journal (Published June 23, 2016) http://www.abajournal.com/news/article/supreme_court_says_warrantless_blood_tests_incident_to_drunken_driving_arre

vi See Arizona DUI: Refusal to Take a Blood, Breath, or Urine Test Driving Laws NOLO Legal Encyclopedia (July 1, 2016) http://dui.drivinglaws.org/resources/dui-refusal-blood-breath-urine-test/arizona.htm

vii Id.

viii Id.

ix Id.

x Id.

xi See Challenging the Blood Test in a DUI Case Driving Laws NOLO Legal Encycloedia (July 1, 2016) http://dui.drivinglaws.org/resources/dui-and-dwi/dui-defense/challenging-blood-test-dui-case.htm

xii Id.

xiii Id.

xiv Id.

xv Id.

xvi See Arizona DUI: Refusal to Take a Blood, Breath, or Urine Test Driving Laws NOLO Legal Encyclopedia (July 1, 2016) http://dui.drivinglaws.org/resources/dui-refusal-blood-breath-urine-test/arizona.htm

xvii Id.

xviii See Supreme Court Says Warrantless Blood Draws in DUI Arrests are Unconstitutional ABA Journal (Published June 23, 2016) http://www.abajournal.com/news/article/supreme_court_says_warrantless_blood_tests_incident_to_drunken_driving_arre

xix Id.

xx Id.

xxi Id.

xxii Id.

xxiii Id.

xxiv Id.