WASHINGTON — The Obama administration’s announcement that it planned to question the Boston Marathon bombing suspect for a period without first reading him the Miranda warning of his right to remain silent and have a lawyer present has revived a constitutionally charged debate over the handling of terrorism cases in the criminal justice system.

The suspect, Dzhokhar A. Tsarnaev, 19, a naturalized American citizen, remained hospitalized on Saturday for treatment of injuries sustained when he was captured by the police on Friday night, and it was not clear whether he had been questioned yet. But the administration’s effort to stretch a gap in the Miranda rule for questioning about immediate threats to public safety in this and other terrorism cases has alarmed advocates of individual rights.

Anthony D. Romero, the executive director of the American Civil Liberties Union, said it would be acceptable for the Federal Bureau of Investigation to ask Mr. Tsarnaev about “imminent” threats, like whether other bombs are hidden around Boston. But he said that for broader questioning, the F.B.I. must not “cut corners.”

“The public safety exception to Miranda should be a narrow and limited one, and it would be wholly inappropriate and unconstitutional to use it to create the case against the suspect,” Mr. Romero said. “The public safety exception would be meaningless if interrogations are given an open-ended time horizon.”