In last June's decision in Hudson v. Michigan, the Supreme Court held 5-4 that the newly-constitutionalized common-law "knock and announce" rule — a rule that an officer executing a warrant normally has to knock, announce his presence, and then wait a bit before forcibly entering a home — is not enforced with an exclusionary remedy. In an opinion handed down on Friday, Judge Moylan of the Maryland Court of Special Appeals points out the very interesting questions that would have been raised in suppression hearings if Hudson v. Michigan had gone the other way:

  This case had promise of leading us to a hidden treasure trove of intriguing nuances about the phenomenon (or phenomena) of knocking and announcing, had not that inquiry been unceremoniously short-circuited by Hudson v. Michigan, 547 U.S. ____, 126 S. Ct. 2159, 165 L. Ed. 2d 56 (2006).
  A vintage conundrum has always been that of whether there is any sound when a great tree falls in a forest but no animal ear is within range of the percussive impact. The answer depends, of course, upon one's conceptualization of sound. The same spirit of intellectual inquiry leads us to wonder whether it makes any difference if a policeman enters a home without knocking if there is no one within to hear a knock in any event. That answer will depend upon the purpose of the knock. Is it to give notice to an occupant of an impending police entry or is it only a mechanical drill movement in a required manual of arms?
  Another intriguing question, also rudely aborted by Hudson v. Michigan, is that of how to knock (or should one knock) on an open door. And how does one knock if there is no door at all? How does one knock on the flap of a tent? Should one knock on a classical Japanese paper house if the result would be a fist through the wall? Should the police carry a knocking board with them as standard equipment? Will we ever be reduced to measuring a knock's decibel level or to evaluating its acoustical carrying power? Was it for this that the embattled farmers stood at Concord Bridge? We were well on the way to drowning in contentious urging such silliness and triviality when Hudson v. Michigan administered a merciful coup de grace.
  Intertwined with these questions, of course, is the tantalizing semantic teaser of whether "knock and announce" is a single indivisible phenomenon or a double-barreled requirement in the unforgiving conjunctive. If the announcement of police presence is loud and clear, is a subsequent (or an antecedent) knock a relentlessly additional Fourth Amendment prerequisite, or is it merely an exclamation point? If the giving of notice is the animating purpose, does not the announcement alone do the trick? Is a police entry after a proclamation, with a bullhorn, "Put your hands in the air; we're coming in," unreasonable without an attendant knock? In short, is not the pairing of the words "knock and announce" nothing more than a linguistic convention akin to "goods and chattels" or "give and bequeath"?

  Interesting law geek questions — and no doubt the kinds of questions that helped get five votes for the view that suppression of evidence should not hinge on the answers.

  Thanks to fourthamendment.com for the link.