SINCE its adoption after a landmark 1966 Supreme Court decision, the Miranda warning has worked its way into not only everyday police procedure, but American culture as well — even if you’ve never been arrested, you probably know the words “anything you say can and will be used against you.”
But as the Obama administration considers carving out an exception to the Miranda rules for terrorism suspects in the wake of the arrest of Faisal Shahzad, the Connecticut man accused of being the Times Square bomber, it’s important to note how little most people understand what Miranda does and doesn’t mean.
First and foremost, the failure to give a Miranda warning does not result in a case being dismissed. It only results in the inability of the police to use a confession and its fruits in evidence. Indeed, the overwhelming majority of successful criminal prosecutions do not involve confessions.
The warning’s genesis lies in the Fifth Amendment, which says that the government may not compel a person “in any criminal case to be a witness against himself.” The framers knew how easy it was to obtain a confession through torture or other forms of overt coercion, and how tempting it was for a government to use such tactics. To prohibit this kind of abuse, the founders said, in effect, that a person could not be forced to confess.
http://www.nytimes.com/2010/05/13/opinion/13wachtler.html?th&emc=th