> The protection in the Fifth is to prevent a perverse system of coerced confessions, where innocent people can be placed on the stand and forced to falsely confess before the court.
Do you have a source for this claim? Compelled confessions are already invalid. I'm skeptical that this was the primary purpose of the amendment.
Compelled confessions are not "already invalid" separate from the Fifth Amendment. To the extent that statutory restrictions prevent it, that arises from the same impulse of the Fifth and is most likely primarily intended to be supplementary thereto.
The right against self-incrimination is intended to establish a system of justice that requires prosecutors to obtain real proof rather than making it dependent on manipulating the accused, who may well be innocent, into believing that a confession is the only way out (that is, confessions extracted by coercion).
Similar rights existed in multiple state constitutions prior to the ratification of the federal constitution. Note also that incorporation didn't begin to occur until the late 1800s-early 1900s, so independent state statutes protecting this right would've been necessary, and their existence doesn't mean that the Fifth didn't also target this protection.
>The Fifth Amendment [...] was created in reaction to the excesses of the Courts of Star Chamber and High Commission. [...] These courts utilized the inquisitorial method of truth-seeking as opposed to the prosecutorial, meaning that prosecutors did not bear the burden of proving a case, but that sufficient "proof" came from browbeating confessions out of the accused. [...] With the abolition of the Courts of Star Chamber and High Commission, the common law courts of England incorporated this principle of nemo tenetur—that no man should be bound to accuse himself. By the 18th century, English law provided that neither confessions coerced during the trial nor pretrial confessions obtained through torture could be used. This was based on the belief that coerced confessions were inherently unreliable.
Do you have a source for this claim? Compelled confessions are already invalid. I'm skeptical that this was the primary purpose of the amendment.