Is there any case law where a witness has been coerced to testify in a criminal case?

While appellant is correct that a conviction founded upon testimony coerced by the state would violate basic due process (see People v. Medina (1974) 41 Cal.App.3d 438, 455-456, 116 Cal.Rptr. 133), no showing of such coercion was made in this case. In Medina, the court found a violation of due process where the immunity of accomplice witnesses was expressly conditioned upon their agreement to testify in a particular fashion. (Ibid.)

It is also an obvious denial of due process to offer immunity to a witness on

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