Should he ever regain consciousness, alleged Boston Marathon bomber Dzokhar Tsarnaev will face extensive questioning from law-enforcement. He may or may not receive a Miranda warning before this questioning ("You have the right to remain silent. . . ." yadda yadda yadda), Authorities may skip the warning in exigent circumstances where aggressive questioning could possibly ward off imminent threats. But considering the fact that a week has passed since the Marathon bombings, as well as the fact that Tsarnaev will likely remain unconscious for a while yet, I fail to see how a case for "exigent circumstances" can be made. More to the point, though, I wonder what it would mean for the authorities not to Mirandize the suspect.
The Miranda warning arose in response to a Supreme Court decision where a prisoner's confession (Miranda's confession, coincidentally enough) was disallowed (and his case ultimately dismissed) because police failed to warn him of his constitutional right to remain silent. In Tsarnaev's case, though, prosecutors are willing to take the chance that they will not be able to use any confession he might give, as they feel they have enough eyewitness and forensic evidence to mount a successful prosecution even without it.
In a sense, the standard Miranda warning is largely superfluous for anyone who has spent a significant amount of time in the United States. Anyone who has seen an episode of "Law and Order" can recite the whole thing by heart. As an American citizen and someone who went to Dartmouth (although he didn't do so great in chemistry), Tsarnaev is presumably knowledgeable of his constitutional rights, warning or no. But does the fact that authorities don't have to Mirandize Tsarnaev mean that Tsarnaev has no right to remain silent? And if that's the case. . .well then what? Are we headed for Abu Ghraib in the Bay State?