Random hypthetical: Imagine you are charged with a crime, and know for certain a witness can exhonerate you beyond any reasonable doubt. Maybe they don't like y

Random hypthetical: Imagine you are charged with a crime, and know for certain a witness can exhonerate you beyond any reasonable doubt. Maybe they don't like you, maybe they have something to gain from a guilty verdict. But you also know their testimony would not incriminate them at all -- they are also innocent, and the 5th amendment does not apply. You have a fifth amendment to witnesses in your defense, which this person is denying you. It seems reasonable to me that a coercive power like this should exist, even if we disagree with any given specific application of it.