The issue goes back to 1980 when police in the Queens borough of New York received a call that a woman said she had been raped and the suspect was in a supermarket carrying a gun. A police officer ended up apprehending a suspect who had an empty shoulder holster.
After the police officer handcuffed the suspect, he asked him where the gun was. The suspect nodded toward some cartons. The officer retrieved the gun, formally arrested him, and read the man his Miranda rights. The man said that he would answer questions without an attorney present and that he owned the gun.
The trial court excluded the statement and the gun as well as his other statements because of the Miranda violation. This was affirmed by an appeals court. But in 1984, the US Supreme Court overturned the lower courts and said that in this case, public safety (finding the gun) was more important than the Miranda warning.
In recent years, the Justice Department seems to have decided to expand the public-safety exception to include other types of intelligence, Birckhead says.
She cites a 2010 DOJ memorandum to the FBI obtained by The New York Times, which stated that after all public-safety questions may have been asked, “agents nonetheless conclude that continued unwarned interrogation is necessary to collect valuable and timely intelligence not related to immediate threat, and that the government’s interest in obtaining this intelligence outweighs the disadvantages of proceeding with unwarned interrogation.”
How that intelligence gets used is also open to question.
For example on Thursday, New York Mayor Michael Bloomberg and New York Police Commissioner Raymond Kelly said that during the interrogation of Mr. Tsarnaev, he indicated he and his brother Tamerlan, who was killed, had planned to go to New York to set off bombs in Times Square.