By John McDevitt

PHILADELPHIA (CBS) – The Boston Marathon bombing suspect, Dzhokhar Tsarnaev, was not be read his Miranda rights because the government is invoking the rare public safety exception.

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Without the standard Miranda Rights issued, a suspect is not reminded of his right to remain silent. And anything he says could be used against him in the court of law.

It allows law enforcement to engage in a limited and focused unwarned interrogation within 48 hours.

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Philadelphia District Attorney Seth Williams says the public safety exception is rare and done when there is an immediate danger to the public.

“(It’s) to prevent a future catastrophe; to ask very narrow questions. The answers to those questions would then be used to prevent the catastrophe that could also be used against a defendant in court despite not having not been apprised fully of his right to remain silent.”

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The public safety exception was invoked in 2009 in the underwear bomber case in Detroit and in 2010 in the attempted bombing in New York City’s Times Square.