On April 17, 2013, the United States Supreme Court held in Missouri v. McNeely, No. 11–1425 that, as a general rule, police must obtain a search warrant or consent in order to extract blood from a driver to test for alcohol.
Blood-alcohol levels are typically based on Alcotest breath samples, with police resorting to extraction of blood where the Alcotest cannot be used. For example, when the driver has been injured, has bad asthma or for some other reason cannot provide a sample, New Jersey courts have allowed police to require blood testing so long as it is not performed forcibly or against physical resistance.
Previously, the fact that the passage of time caused a drop in a driver's blood-alcohol level was deemed a sufficient exigency to justify an exception to the Fourth Amendment warrant requirement for searches. Under McNeely, however, the drop in levels may support an exigency finding in a particular case, but does not do so categorically. Thus, the issue must be decided on a case by case basis, based on the totality of the circumstances, including the possibility of loss of blood alcohol level evidence as time passes.
It is anticipated that the McNeely decision will result in an increased number of defense motions to suppress evidence of blood alcohol levels that were obtained by blood extraction.