Taking Blood Evidence for Granted: McNeely and Birchfield's Unintended Consequences

Abstract

Drawing blood from a suspect’s body for purposes of criminal investigation implicates substantial constitutional, privacy, and ethical concerns. And yet blood tests provide unique benefits over breath or urine analysis, motivating states to ensure their availability. Law enforcement officers must presumptively use warrants to obtain blood samples from driving-under-the-influence (DUI) suspects. They have long relied on three recognized exceptions to forgo warrants and more readily obtain samples before evidence dissipates from suspects’ bloodstreams. Then, in just two decisions only three years apart, the Supreme Court invalidated one of these exceptions as justification for a warrantless blood draw in the mine-run DUI case, see Missouri v. McNeely, 569 U.S. 141 (2013); entirely eliminated a second exception, see Birchfield v. North Dakota, 136 S. Ct. 2160 (2016); and curtailed use of the third exception, consent, where defendants’ “consent” follows from widely used “implied consent” laws, see id. The Court assured states that limiting warrantless blood draws in these ways would not weaken their DUI cases because implied consent laws are still generally permissible, and if all else fails, police can use warrants to obtain the needed evidence.

This paper undertakes the first-ever nationwide analysis of state laws governing law enforcement’s collection of blood-sample evidence to argue that despite the Court’s reassurances, McNeely and Birchfield fractured the foundations of DUI evidentiary regimes previously taken for granted. Pre-Birchfield scholarship has surveyed state statutes authorizing forced blood draws in order to explore the ethical and legal implications for doctors who facilitate such draws. And since Birchfield, commentators have distilled its legal principles and their immediate implications for lawyers, legislatures and courts. This paper goes much further, surveying state statutory, judge-made, and constitutional law to develop a comprehensive picture of states’ capabilities and the legislative tasks they face post-Birchfield if they intend to continue using blood draws in a constitutional manner.

The paper proceeds in four parts. Part I lays out the relevant legal landscape. It explains the Fourth Amendment’s application to blood draws and the four justifications — three warrant exceptions and the warrant power itself — that states have historically relied on to obtain evidence of intoxication. It then summarizes McNeely and Birchfield’s recent rapid evolution of Fourth Amendment doctrine regarding the three exceptions’ applicability to blood draws in criminal investigations. Part II argues that curtailing the first two exceptions has left implied consent regimes more susceptible to direct attack. Given its current trajectory, the Supreme Court is poised to further limit these laws in Mitchell v. Wisconsin, on which it heard argument in late April 2019. Next, Part III tests the Court’s repeated assumption in McNeely and Birchfield that if even the consent exception is unavailable, warrants offer a backstop for law enforcement’s evidentiary needs. In its Conclusion, the paper puts the choice to state legislatures in crafting a balance — between states’ interest in effective and efficient enforcement of DUI laws and suspects’ constitutional rights — consistent with the principles announced in McNeely and Birchfield.

Keywords: Fourth Amendment, blood, DUI, DWI, OWI, consent, implied consent, blood draw, blood test, McNeely, Birchfield, warrant, search, civil liberties, civil rights, privacy, Schneckloth, Mitchell, search incident to arrest, exigency, exigent circumstances