Or the government could try to persuade a judge that any confession by Mr. Tsarnaev resulting from such an interrogation could be used as evidence against him under the "public safety" exception to the Miranda rule.

WSJ: Prosecutors Plot Strategic Course in Boston Bombing Case

Executive Director Anthony Romero said the legal exception applies only when there is a continued threat to public safety and is "not an open-ended exception" to the Miranda rule, which guarantees the right to remain silent and the right to an attorney.

NPR: Boston Bomb Suspect Hospitalized Under Heavy Guard

Federal agents at first questioned Tsarnaev without reading him his Miranda rights, under an exception to the rule invoked when authorities believe there is an imminent public safety threat, a Justice Department official said over the weekend.

CNN: Boston bomb suspect: My brother was the mastermind