Blood Alcohol Concentration

Definition: Challenges related to the collection of BAC testing results from suspected impaired drivers that require emergency medical treatment for their crash-related injuries can have major implications on evidence in DUI legal cases.

Executive Summary: Law enforcement officers are often equipped to collect evidence needed to confirm the presence of alcohol as a contributing factor in crashes involving a suspected impaired driver; however, failure to immediately collect such information may lead to a weak evidence base or issues related to the admissibility of such evidence in court proceedings. Law enforcement officers should be familiar with state and local laws regarding the collection of BAC testing results in emergency departments, hospitals or other off-site locations. Testing should occur within hours of a motor vehicle crash, assuming the law enforcement officer has probable cause to collect results.

More Detail: After a fatal or serious injury crash occurs, the immediate screening of the driver is a critical step in identifying the contribution of alcohol to the crash. Furthermore, due to the natural processing of alcohol by the human body, quickly obtaining evidence generally improves its accuracy and reliability. Law enforcement officers are often equipped to collect evidence needed to confirm the presence of alcohol as a contributing factor in crashes involving a suspected impaired driver; however, injuries sustained by the driver during the crash may require emergency treatment. Therefore, the investigating officer may not have the opportunity to acquire an on-scene breath or blood sample.

Medical treatment facilities are generally equipped to determine the driver’s BAC with blood samples drawn for medical purposes. For evidentiary purposes a separate blood sample may be required, in which case, it is important to establish an evidentiary chain of custody to ensure the sample belongs to the driver and has not been contaminated from the time the sample is drawn, to the time it is introduced as evidence in court during prosecution.

In states that do not require BAC testing after fatal crashes, law enforcement officers are responsible for promptly requesting that medical staff draw a blood sample for BAC analysis or, if admissible in court, provide the results from the facility’s own analysis. Also, before making such a request, the officer must meet certain legal requirements regarding probable cause, implied consent, and other state requirements. It may also be necessary to get a search warrant before a blood draw. These standards, even if considered relatively low, may prove difficult to meet in some instances, particularly if emergency personnel remove the driver from the crash scene before law enforcement arrives. Police should be familiar with the laws pertaining to medical cooperation and be prepared to recite  them to doctors and nurses to “encourage” cooperation.

How to handle BAC after fatal crashes where the suspected DUI operator is taken from the scene to the hospital for examination and/or treatment of his/her crash related injury is the most difficult DUI detection case police arriving at the scene will have to face. Again, knowledge of the local law is key to successfully bringing a charge and obtaining a conviction. In such a case, not only must the officer at the scene be fully conversant regarding the law, he/she would be best served with immediate access to a prosecutor for legal advice on the varying conditions an officer might confront at the scene or at the hospital. Law enforcement readers may see a need to raise the issue with their leadership/prosecutor’s office for establishing an operational protocol. In this way, everyone can be aware of handling such legally complex situations.


Suggested Audience: Law Enforcement, Prosecutors, Judges


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