There is no better source for keeping up with the United States Supreme Court and few commentators as thoughtful as Lyle Dennison. His post on Missouri v. McNeely’s oral argument is first rate.

“Even allowing for the reality that what is said at a Supreme Court hearing does not necessarily dictate the outcome, now and then a case comes along where the Justices join so obviously in a common pursuit of a compromise that little suspense remains.  That happened on Wednesday, in the case of Missouri v. McNeely (docket 11-1425), when it seemed quite predictable that the Court is not going to let police across the nation order — on their own authority — the taking of blood samples from those suspected of drunk driving.   Police, it would appear, are at least going to have to try to get a search warrant, even though they sometimes will be allowed to do without one.”

See: http://www.scotusblog.com/2013/01/argument-recap-compromise-on-dui-blood-tests/#more-157395.