His logic’s straightforward. It’s easy to prove that Tsarnaev did the deed but in order to prove that he’s a “terrorist” and therefore eligible for the death penalty, you have to also prove that his intent was to terrorize the population. And the only hard evidence of that might be his own statements — which will be inadmissible if a judge rules that the feds the “public safety” exception to Miranda doesn’t apply in this case. I must be missing something, though, because as I read the statute, I don’t see where the feds need to prove any specific terroristic intent. Via Ken at Popehat, here’s the relevant part:

(a) Offense Against a National of the United States or Within the United States.— A person who, without lawful authority, uses, threatens, or attempts or conspires to use, a weapon of mass destruction—

(1) against a national of the United States while such national is outside of the United States;

(2) against any person or property within the United States, and
(A) the mail or any facility of interstate or foreign commerce is used in furtherance of the offense;
(B) such property is used in interstate or foreign commerce or in an activity that affects interstate or foreign commerce;
(C) any perpetrator travels in or causes another to travel in interstate or foreign commerce in furtherance of the offense; or
(D) the offense, or the results of the offense, affect interstate or foreign commerce, or, in the case of a threat, attempt, or conspiracy, would have affected interstate or foreign commerce;

(3) against any property that is owned, leased or used by the United States or by any department or agency of the United States, whether the property is within or outside of the United States; or

(4) against any property within the United States that is owned, leased, or used by a foreign government,

shall be imprisoned for any term of years or for life, and if death results, shall be punished by death or imprisoned for any term of years or for life.

As Ken notes, the Boston Marathon is an activity that “affects” interstate commerce so they’ve got him under subsection (2). Per the statute, a “weapon of mass destruction” is defined as any “destructive device” listed in section 921, which includes “bomb.” It’s true that the statute quoted above is listed in the “Terrorism” chapter of the federal criminal code and Dershowitz is right that “terrorism” as defined in that chapter requires proof that the defendant intended to “intimidate or coerce a civilian population,” but the WMD statute under which Tsarnaev was charged makes no mention of “terrorism.” As I read it, it simply says that if you use a WMD to kill someone and there’s some federal nexus to the crime (i.e. it affects interstate commerce), they can give you the needle. Ken notes that the courts, in interpreting that statute, have added the requirement that the suspect must “knowingly” commit the crime, but that should be easy if the allegations in the complaint are true. Bottom line, I don’t see where the feds need to show any “terrorist” intent on Tsarnaev’s part, even in the sentencing phase, to get death. All they need to show is that he knowingly planted a bomb.

In fact, what may have happened here is that Dershowitz gave this interview to MSNBC before the complaint was released, when he was just guessing at the charges. In another interview this afternoon, given after he read it, he said the feds’ case is “ironclad.” Even so, I admit that I don’t understand why they didn’t Mirandize Tsarnaev just to be on the safe side. It strikes me as exceedingly unlikely that the difference between an accused terrorist talking or clamming up would be a single rote recitation of something a U.S. citizen has heard 8,000 times on cop shows before. In all probability, if he’s not going to talk, it’s because he’s resolved to be a tough guy, not because he’s under some misimpression that he’s duty-bound to speak to the police. And if he is talking, I’d guess it’s because he thinks either (a) cooperating might earn him a life sentence instead of death or (b) that the CIA might beat it out of him if he doesn’t, Miranda warnings or no. Also, hasn’t Tsarnaev already had a lawyer appointed to him? If you look at page two of the complaint, there’s an attestation that a copy of the motion has been served on “counsel for the defendant.” If he’s already got a lawyer advising him on what he should or shouldn’t do, what’s the sense in not Mirandizing him at this point? The lawyer will tell him his rights even if the feds don’t.

Update: Well, there you go. The timing is unclear but I think it happened sometime today:

Question for legal eagles: If he makes incriminating statements before they’ve Mirandized him, when he’s being grilled by the High-Value Detainee Interrogation Team, and then they Mirandize him and ask him to repeat what he said before, is that good enough to make the statements admissible? Or will a judge rule that Mirandization after the fact can’t remove the element of coercion that produced the incriminating statements originally?

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