To see why I think the results of Al-Marri are so puzzling, consider the following hypothetical. An Al-Qaeda cell of five individuals, all citizens of Qatar, enter the United States on student visas. The cell members' plans are to detonate a "dirty bomb" in New York City, and they rent a hotel room in Jersey City, New Jersey (just across the river) to build the dirty bomb. One of the hotel employees thinks the group is suspicious, and he calls up the local police and tells an officer that there is a group of Arab men in the hotel staying in one room and acting very secretively.
The officer visits the hotel when the men are out one day and he requests that the hotel employee show him the room. The employee agrees; he opens the door with his key and shows the officer inside. They immediately see the bomb-making materials along with several photographs of Osama bin Laden and the 9/11 attacks taped to the walls. The officer contacts the FBI and the Department of Homeland Security. An hour later, the FBI has obtained a search warrant for the room and arrest warrants for the five men.
The men are arrested and charged criminally. A search of the hotel room discovers all the bomb-making materials. The room search also uncovers videotapes the men made celebrating their pending attack; the men each spent a few minutes on tape describing what attacks they will execute and hoping and praying that the streets of New York will "run red with Jewish and imperialist blood."
But there's a major problem with the criminal case: The evidence against the cell members was obtained in violation of the Fourth Amendment. Under Stoner v. California, the men have a reasonable expectation of privacy in the hotel room and the hotel clerk lacks authority to consent to a law enforcement search. As a result, the evidence against the five men was obtained in violation of their Fourth Amendment rights. The evidence -- including the videotapes in which they each celebrated the attacks and confessed to their plans -- must be suppressed.
Later, after a long comment thread full of mostly skeptical comments (pretty natural, since we've all seen this hypo before in law school), Prof. Kerr made another post to explain "the continuum between war and crime." In it, he creates a list of scenarios and asks readers to think about whether they should be handled under the "war" rules or the "crime" rules.
The problem with Prof. Kerr's premise is that he has in one of the most common poker leaks amongst amateur players: results-oriented thinking. This leak is at play every time some player tells you about how he folded 77 to a big preflop raise, but then the flop came 773 (which would have given him the four 7s for the nuts). The only way he can justify playing a medium hand like 77 in the face of a big raise is to talk about what happened after the flop; it doesn't make sense to play it if you don't know what cards are going to come next.
Prof. Kerr's hypothetical is useless, because it assumes we know everything about this "al-Qaeda cell" when we're making the decision about how to play the game. In the real world, we don't know everything about every suspect and we can't decide how to play the game based on assumptions about what's going to happen in advance. That's never the case in reality.
In the real world, you have to decide how you want to play the game without knowing what everyone else is holding or what's going to come out on the flop. You can play poker playing every hand in the hope that you'll draw lucky. It's stupid, but you'll only lose your money (probably to people like me).
We can't play the game of law enforcement that way, though, since we'll end up losing something much more important than money. We'll end up losing our civil liberties.