In divided ruling, SCOTUS embraces (fuzzy?) standard rather than per se rules for DUIs and blood tests

The Supreme Court this morning handed down a notable, and notably divided, Fourth Amendment ruling in Missouri v. McNeely, No. 11-1425 (S. Ct. April 17, 2013) (available here). This accounting of the votes and opinions highlights why it likely will not be easy to figure out right away just what McNeely really means:

SOTOMAYOR, J., announced the judgment of the Court and delivered the opinion of the Court with respect to Parts I, II–A, II–B, and IV, in which SCALIA, KENNEDY, GINSBURG, and KAGAN, JJ., joined, and an opinion with respect to Parts II–C and II, in which SCALIA, GINSBURG,and KAGAN, JJ., joined. KENNEDY, J., filed an opinion concurring in part. ROBERTS, C. J., filed an opinion concurring in part and dissenting in part, in which BREYER and ALITO, JJ., joined. THOMAS, J., filed a dissenting opinion.

I will leave it to Fourth Amendment gurus to tell me whether there is as much of interest in the substance of McNeely as there is in the voting blocks.  And speaking of substance, here is how the main opinion of Justice Sotomayor gets started:

In Schmerber v. California, 384 U. S. 757 (1966), this Court upheld a warrantless blood test of an individual arrested for driving under the influence of alcohol because the officer “might reasonably have believed that he was confronted with an emergency, in which the delay neces­sary to obtain a warrant, under the circumstances, threat­ ened the destruction of evidence.”  Id., at 770 (internal quotation marks omitted).  The question presented here is whether the natural metabolization of alcohol in the bloodstream presents a per se exigency that justifies an exception to the Fourth Amendment’s warrant require­ment for nonconsensual blood testing in all drunk-driving cases.  We conclude that it does not, and we hold, con­sistent with general Fourth Amendment principles, that exigency in this context must be determined case by case based on the totality of the circumstances.

In the context of the Fourth Amendment (and many other criminal procedure contexts), I  typically see the embrace of multi-factor standards rather than bright-line rules to be better for defendants (and especially their lawyers) than for police and prosecutors.  In turn, the voting blocks here in McNeely reinforce my sense (1) that Justices Ginsburg, Kagan and Sotomayor are very often going to vote together in criminal procedure cases, and (2) that, at least in pre-trial procedure settings, Justice Scalia may often be a more consistent pro-defendant vote than either Justice Breyer or Justice Kennedy.