It would seem to be an obvious principle of justice that, in any criminal prosecution, the accused should have the right “to be informed of the nature and cause of the accusation” against him. Indeed, it was such an obvious principle to the American Founders that they rarely had anything to say about it. Several state constitutions had included guarantees that were similar to the one found in Virginia’s Declaration of Rights: “That in all capital or criminal prosecutions a man hath a right to demand the cause and nature of his accusation.” The wording may have changed slightly between states, but its meaning was always clear: the state could not lock up a person without explaining why—abusing this principle has been the privilege of tyrants throughout history.
There are other reasons why it is necessary to inform a suspect of the nature of the accusation against him. Perhaps the most compelling is that a suspect could not prepare an effective defense unless he knew the particulars of the charge. Finally, if the state could arrest an individual, keep him incarcerated, and question him, all without informing him of its reasons for doing so, then it would nullify many of our other rights.
The 6th Amendment right of a suspect “to be informed of the nature and cause of the accusation” is closely tied to at least three of the protections found in the 5th Amendment. It is the job of the Grand Jury, after all, to specify (or “inform”) in an indictment what are the particular charges against the accused. And this indictment is also necessary for ensuring that the accused shall not “be subject for the same offence to be twice put in jeopardy of life or limb.” Unless the prosecutor is compelled to be specific about the charges against a suspect before he is brought to trial, there would be no way to test whether a suspect was being subjected to “double jeopardy” for the same offense. Finally, this provision enables the prisoner to guard against self-incrimination. If a defendant knows the nature and cause of the accusation, then he will be a better judge of the purpose of any questions that the police or the prosecutor might ask. He will be more likely to know which answers will have the tendency to make him “a witness against himself.”