Whether or not the 5th Amendment to the Constitution, as well as the adjudicated Miranda warning, effectively means that self-incrimination or a confession is thus always permitted per United States law, has been previously determined by a multitude of court cases, which thus demonstrates that self-incrimination or a confession, made under the appropriate circumstances as outlined by the 5th Amendment in conjunction with the Miranda warning are, in fact, admissible in a court of law. That is to say, those that confess to a given crime, whether or not this is factually true, or self-incriminate themselves, whether or not this is factually true, will typically be subject to having that incriminating statement or confession, be an integral part of their court case.
Perhaps this is the way that it should be; but what has to be admitted is that, to begin with, not every nation sees self-incrimination or a confession in the same way. In fact, historical Jewish law, bans self-incrimination and confessions from being admissible evidence, thereby proving the point that in certain countries, that there is an inherent belief that self-incrimination and confessions have no legitimate role to play in a criminal trial. After all, the world is full of situations in which many a person will confess to their guilt, because their mind is not right, or because they have been coerced, or because they have been intimidated or tortured, or because they are clinically depressed, or because they desire notoriety, or because they are in an untenable situation, or because they are forsaken, or even for the notoriety of such.
That said, there are an awful lot of people, that believe that anyone that incriminates themselves or confesses to a crime, should most definitely be held accountable to that crime in a court of law for having made that admission. Yet, recognize that there are multitude of ways that an incrimination can occur, or a confession be made; of which, none of these ways can be, in absence of supporting evidence, be determined to be actually the whole truth, of which, a criminal trial should always have as it basis, a determination to get to truth and fact. That is to say, there are those people that claim that they are God or Christ, or some other senseless nonsense, of which, these claims are typically relatively easy to prove as being false. So too, not everything so stated by anyone, should be believed, without suitable questioning and evidence behind such, so as to ascertain then its veracity.
Further to the point, any criminal trial, in which the guilt of the defendant is primarily built around that defendant’s confession, isn’t really a trial, at all; but basically, this is a “show trial”, so meant to get the result so desired in accord with the public perception of what has occurred, without the true facts of the case, getting a fair shake, whatsoever. Remember this well, not all that glitters is gold, and not everyone that confesses to a crime or admits to this or that, has actually done so; for they may have been coerced into saying such, or they might be hopelessly confused or inept– which is why criminal trials should always be about the search for truth and to determine facts, and thus not to be reliant upon confessions, whatsoever.