Dershowitz also said statements made by police in Boston seems to contradict the government's reasons for invoking the public safety exception.

CNN: What's next for the Boston Marathon bombing suspect?

The public safety exception does not set a hard time when questioning must stop and the suspect must be taken into court, but it's generally understood to be about 48 hours.

CNN: SHARE THIS

The government has invoked the public safety exception, a designation that allows investigators to question the teen without reading him his Miranda rights and without a lawyer present, another Justice Department official, also speaking on condition of anonymity, told CNN.

CNN: Official: Boston bombing suspect 'sedated'