WASHINGTON – The White House’s decision to interrogate the suspect in the Boston Marathon bombing without first warning him of his rights has sparked criticism from both sides of the political spectrum about the best way to prosecute terrorism cases.

Justice Department officials have said their move to question bombing suspect Dzhokar Tsarnaev, 19, without reading him the Miranda warning of his right to remain silent is a necessary legal tool in cases of domestic terrorism.

Civil liberties groups said Saturday the tactic raises concerns about infringement of Tsarnaev’s constitutional rights, especially since he is a naturalized American citizen. At the same time, four Republican lawmakers criticized the administration for not being tough enough, saying Tsarnaev should be designated an enemy combatant with no right to counsel.

“These kinds of cases, which are going to be with us going forward, they’re very difficult because this is all uncharted territory,” Robert Chesney, a professor of constitutional and national security law at the University of Texas, said Saturday.

After a week of uncertainty and a manhunt that included more than 1,000 federal agents, the capturing of Tsarnaev has swung the focus of the bombing investigation into the courts. Federal prosecutors are drafting a criminal complaint and interrogators are preparing to question the suspect on his knowledge of other plots or associates, according to federal law enforcement officials.

A team of counterterrorism interrogators with representatives from the Federal Bureau of Investigation, Central Intelligence Agency, and the Defense and State departments, is in Boston to question the suspect, a Justice Department official said.

Questions will focus on possible links to terrorist groups and associates that may have been involved in the bombing or its planning, said the official, who asked not to be identified because the move wasn’t announced. Statements collected during that period can be used by prosecutors in court.

For the administration of President Barack Obama, the decision to invoke the so-called public safety exception represents something of a middle ground. It gives interrogators flexibility in questioning as they work to discover new information about terrorist attacks while laying the groundwork for a criminal trial.

The Democratic administration has taken a “relatively apolitical position” in deciding to use the exception in the Tsarnaev case, said Stephen Vladeck, a national security law professor at American University in Washington, D.C. It would have been a “cave-in” to pursue anything else, he said.

The Republican lawmakers said Saturday the limited period used to question the suspect before giving the Miranda warning, estimated to be at most 48 hours, would hinder the investigation.

Relying on the exception instead of designating Tsarnaev an enemy combatant “could severely limit our ability to gather critical information about future attacks from this suspect,” Sens. Lindsey Graham of South Carolina, John McCain of Arizona, Kelly Ayotte of New Hampshire and Rep. Peter King of New York, all Republicans, said in a statement.

The exception to the Miranda warning stems from a 1984 Supreme Court decision that allows law-enforcement officials to question suspects about threats to public safety before they are warned of their rights to remain silent and have an attorney present.

“In practice, the public-safety exception is really limited,” Vladeck said. “It’s not a sort of get-out-of-Miranda-free card.”

Attorney General Eric Holder has pushed for the aggressive use and expansion of the warning exception in cases that involve terrorism. Holder and his top aides in 2010 lobbied congressional lawmakers to pass a law that would codify in statute flexibility for prosecutors in the interrogation of terrorism suspects.

With little appetite on Capitol Hill to re-enter the national security law debates that came to define Republican President George W. Bush’s administration, the plan did not advance, according to Matthew Miller, a former top aide to Holder.

“The reaction from Capitol Hill was that they didn’t want to open this can of worms,” said Miller, who is now a partner at Vianovo, a crisis strategy firm.

Holder, along with the FBI, opted to instruct prosecutors and agents to use the exception when it came to the “interrogation of an operational terrorist in the United States.”

The FBI’s guidance to its agents said that because of the magnitude and complexity of terrorist plots and organizations, “the circumstances surrounding an arrest of an operational terrorist may warrant significantly more extensive public safety interrogation than would be permissible in a criminal case,” Holder wrote in an October 2010 memo to U.S. attorneys.

Holder’s push has been criticized by civil liberties groups that say delaying Miranda warnings poses risks to the constitutional rights of suspects.

“Obama’s Justice Department unilaterally expanded the ‘public safety exception’ to Miranda in 2010 beyond anything the Supreme Court ever authorized,” Vincent Warren, the executive director of the Center for Constitutional Rights, a legal advocacy group that focuses on civil-liberties litigation, said in a statement Saturday. “Each time the administration uses this exception, it stretches wider and longer.”

Anthony Romero, executive director of the American Civil Liberties Union, urged caution with the exception’s use in Tsarnaev’s case.

“The public safety exception should be read narrowly,” Romero said in a statement.

Another wrinkle in this case is Tsarnaev’s status as a U.S. citizen, which will create challenges in designating him an enemy combatant, said Benjamin Wittes, a senior fellow at The Brookings Institution who focuses on national security law and the war on terrorism. Brookings is a Washington-based public policy organization.

Tsarnaev became a naturalized U.S. citizen on Sept. 11 last year, according to two government officials briefed on the matter. In two previous cases in which the Bush administration designated U.S. citizens enemy combatants, federal officials had to reverse course after a court ruling and pressure by civil liberties groups.

“The lesson of that for the Bush administration and then to the Obama administration was basically: ‘Don’t try this again,’ ” Wittes said.

It also remains unclear what, if any, relationship Tsarnaev has with terrorist groups — a legal requirement for use of the designation, Wittes said.

Holder’s decision to seek changes on Capitol Hill, and the FBI guidance that eventually followed, came amid an uproar over the use of Miranda warnings in the arrests of Umar Farouk Abdulmutallab in 2009 and Faisal Shahzad in 2010.

Abdulmutallab, who pleaded guilty to an attempt to bomb a Detroit-bound airplane on Christmas Day, was questioned by FBI agents without a Miranda warning for about 50 minutes. Shahzad, who attempted to blow up a car in New York’s Times Square, was questioned for days with no warning. Both men were convicted and sentenced to life in prison.

In both cases, Republican lawmakers criticized the administration for eventually giving the suspects their Miranda warnings, even after first invoking the public-safety exception. The criticism was harsh in Abdulmutallab’s case, because he did not cooperate for several weeks after being given the warning.

Abdulmutallab eventually relented and again began cooperating with law-enforcement officials. The administration said this shows the success in gaining valuable information after giving Miranda warnings in both cases.

In Tsarnaev’s case, however, the debate may not matter because of the large volume of evidence that appears to have been collected in the five days since the bombing.

“It’s largely an academic debate, at least in this case,” Vladeck said. “It’s not going to come down to what he may be saying in this pre-Miranda interrogation.”