No, they shouldn't be able to do anything they want. The 8th amendment states that there can be no cruel and unusual punishments. If we disobey the constitution, then we will be hypocrites. When a person is desperate for life, they will most likely say anything to stay alive. It is unconstitutional and it is unreliable.
what if the terrorist isnt telling us information that we know they have? we need to be able to do something to get the information out of them. even if its unconstituitonal.