When Search Warrants Accomplish Very Little

By Sherry Colb

In my Verdict column for this week, I examine the case of Missouri v. McNeely, in which the U.S. Supreme Court recently refused to recognize an exception to the warrant requirement for blood-testing people arrested for DWI.  The stated rationale for the exception -- which the Court rejected -- was that a person's blood-alcohol concentration (BAC) steadily diminshes over time and that therefore, any delay in a blood test (for purposes of obtaining a warrant) will result in the loss of potentially critical evidence of intoxication.  The column considers the compelling nature of the argument for an exigency exception here as well as the Chief Justice's alternative compromise approach.

In this post, I want to consider a different argument, separate from the apparent exigency, for recognizing an exception to the warrant requirement for DWI blood tests:  the relative clarity and uniformity of what it takes to make out "probable cause" in drunk driving cases, the determination that a magistrate would be making in reviewing a police officer's warrant application.

Note first that in order to arrest a suspect for DWI, a police officer needs the same probable cause that she would need to order a blood-alcohol-concentration test of the arrested suspect.  That is, the question for both the seizure of the suspect (arrest) and the search of the suspect (blood test) case is whether the officer has probable cause to believe that the suspect was driving while intoxicated.

In many non-DWI situations, the determination of probable cause is a subtle matter that can accordingly benefit substantially from the neutral input of an objective magistrate.  For example, an anonymous informant might say something incriminating about a suspect, and there might also be some limited but potentially innocent corroboration of the anonymous informant's story from subseqent surveillance, as in Illinois v. Gates.  Magistrates will have an active role to play in such cases in determining whether the facts do or do not amount to probable cause, and their judgment is likely to be less invested in a particular outcome than that of a police officer who receives an anonymous tip.

Drunk  driving cases, however, are different.  Police develop probable cause to believe that a suspect has been operating a vehicle while intoxicated because, typically, a driver has been weaving in traffic and, once stopped, smells of alcohol, slurs his words, has bloodshot eyes, and is perhaps unable to perform basic manual tasks that would demonstrate sobriety.  He may also be unwilling to breathe into a breathalyzer.

With minor variations, these are the facts that amount to probable cause for a DWI arrest and for a BAC test.  The role of the magistrate is accordingly quite limited – she will look at the list of these sorts of facts and then issue a search warrant authorizing a blood test for BAC.  It will be the rare case, in other words, that has a police officer concluding that there is probable cause to believe that a suspect is DWI, but a magistrate reviewing what the police officer says concludes that there is no probable cause.  By now, there is practically a script for what amounts to probable cause for DWI.

There is, then, very little place for a neutral and detached magistrate to resolve ambiguity in a DWI case.  Are there situations in which a DWI suspect shows most or all of the above signs of intoxication but is in fact not under the influence of alcohol?  Of course.  The suspect may be thoroughly exhausted (which, incidentally, can seriously impair driving capacity but does not presently preclude technically lawful driving) or ill or may have suffered a temporary seizure or other medical event.  But that simply means that there is sometimes probable cause to believe that a person is driving while intoxicated when in reality he is not doing so.  Probable cause is entirely consistent with innocence; unlike guilt beyond a reasonable doubt, it leaves in place a significant possibility of innocence, in the interests of gathering evidence and suspects when there is a substantial basis for concluding that a crime has actually taken place.

Notwithstanding my skepticism about the utility of a magistrate's review of probable cause in DWI blood test cases, I am prepared to acknowledge that all other things being equal, obtaining a warrant makes sense.  For one thing, suspects may feel less violated by a nonconsensual blood test if a judge has authorized it, and some police officers may benefit from the supervision entailed in having to articulate probable cause to a magistrate.  This is why I ultimately side with Chief Justice Roberts, who would create a limited exigency for occasions when getting a warrant would delay the blood test, rather than siding with Justice Thomas, who believes that a magistrate's review of probable cause to take a DWI blood test should never be required.

Chief Justice Roberts's opinion deserves praise and respect, I think, because he is not simply pursuing an ideological agenda (whether right- or left-wing) but is instead thinking creatively about how best to accommodate the competing interests at stake in the case.  He has done this before, and his inclination to find viable solutions that parties may not have identified on their own is enormously reassuring, despite the fact that taking a firm stand on one side or the other may be more glamorous or rhetorically satisfying.  I hope he will extend this inclination to other issues on which the Court will be ruling this term.