Just as Hollywood has produced some good movies in trilogies, the United States Supreme Court has produced some good case law in trilogies. The Court addressed the right to confront crime lab analysts with the trinity of Bullcoming, Melendez-Diaz and Williams. On the issue of the need for a warrant to draw blood from a DUI suspect, two-thirds of the triad have been completed: McNeely and Birchfield. The triumvirate is about to be consummated with Mitchell v. Wisconsin.
The Fourth Amendment protects people from unreasonable searches and seizures. The general rule is, for a search to be reasonable, there must be a search warrant issued by a judicial officer. There are many exceptions to that general rule. The question addressed by this tripod of cases is this: when is the government permitted to seize a DUI suspect’s bodily substances without a search warrant?
McNeely and Birchfield
One search warrant exception was analyzed in the first episode of this case law triumvirate: Missouri v. McNeely. McNeely dealt with the exception for searches based on ‘exigent circumstances’: when there is a compelling need for the search and not enough time to obtain a search warrant. The prosecution claimed DUI cases always involve exigent circumstances because the suspect’s blood alcohol concentration decreases with time. The Court concluded the dissipation of alcohol in the bloodstream does not necessarily create exigent circumstances, so a warrant is generally necessary to obtain a DUI suspect’s blood.