Can a defense witness be coerced to testify against himself?

Even accurate advice about the privilege against self-incrimination is inherently coercive when it comes from a prosecutor. "The only respect in which a prosecutor may arguably be better situated than others to provide such advice is that his office actually makes the decision to prosecute. But it is this very power that infects a prosecutorial admonition of the right of a defense witness not to testify with a perilous potential for improper intimidation; and this is so regardless of the propriety in fact of the prosecutor's motives." (People v. Warren, supra, 161 Cal.App.3d at p. 974, 207 Cal.Rptr. 912; see also United States v. Smith, supra, 478 F.2d at p. 979.)

At least one federal case has found that the accused's right to present a defense was abridged when a defense witness was coerced after he had testified. In Berg v. Morris, supra, 483 F.Supp. 179, the witness testified for the defense that he and not the accused had committed the charged robbery. After direct and cross-examination, the court called a recess and informed the witness's attorney that "if he doesn't tell the truth, as we know the truth now to be in view of his prior sworn testimony, under the circumstances of this trial he'll not only suffer a revocation of probation for the felony robbery, but perjury charges will be filed against him." (Id., at p. 181.) The witness was then jailed over the weekend. On Monday, he resumed the stand and recanted his previous testimony.