Decided March 2, 1925
I looked this case up because I've been taught about the "Carroll doctrine" in a couple of different police academies (interesting that they would mention it in NM, because the NM courts have held that it doesn't apply there), and the doctrine certainly gets put to a lot of use in the streets. So I thought that as long as I'm making an effort to really improve my understanding of case law, I should probably familiarize myself with this one. The trouble is that older court opinions can be a little more difficult to get through sometimes, and this one sets the bar really high!
Anyway, there's a lengthy, dry recitation of prohibition laws, some previous search and seizure cases, and English common law. Then there's more of that. Then that goes on for a while longer. Eventually, the court briefly summarizes the facts of this case. The "Carroll boys" were known bootleggers, and government agents had some sort of unspecified evidence that they were currently doing their criminal thing. So the agents were following them from Grand Rapids to Detroit (apparently a hotbed of liquor smuggling activity), but the Carroll boys got away. A couple months later, the officers found the same suspects driving the opposite direction, so they believed that they were now carrying a liquor from Detroit to Grand Rapids to be sold. I don't get how that's PC, but maybe someone who is into drug interdiction can explain the reasoning to me. In any event, the court of the 1920's seemed to like it.* The officers stopped the Carroll boys, searched their cars, and discovered alcohol.
The findings of the court in this case (which are sort of spread out through the whole boring discussion of prohibition/common law/etc) were about what I had been taught before. In it's uniquely wordy style, the court held that "On reason and authority the true rule is that if the search and seizure without a warrant are made upon probable cause...that an automobile or other vehicle contains that which by law is subject to seizure and destruction, the search and seizure are valid." The court explains that the fourth amendment doesn't prohibit searches, it prohibits unreasonable searches, and that while officers applied for a warrant to search a car the car could leave their jurisdiction. The opinion also includes a discussion of the definition of probable cause ("If the facts and circumstances before the officer are such as to warrant a man of prudence and caution in believing that the offense has been committed, it is sufficient").
*Although there was a dissenting opinion, which would have held that there was no reason to stop the car and so the evidence in this case should have been suppressed. The dissenting opinion is much easier to understand... I think we may have got the automobile exception from the court's effort to pretend for a moment that the end justifies the means. Maybe that exception would have come about through a different case if this one had gone the other way, but that's not what did happen.