25 L.Ed.2d 747 (1970). The plea is void if it is “induced by promises or threats which deprive it of the nature of a voluntary act.” Machibroda v. United States, 368 U.S. 487, 493, 82 S.Ct. 510, 513, 7 L.Ed.2d 473 (1962). Coercive acts by third parties unrelated to the government, such as co-defendants, may invalidate guilty pleas. See, e.g., Iaea, 800 F.2d at 867; LoConte v. Dugger, 847 F.2d 745, 753 (11th Cir.1988). The requirements for ascertaining whether a guilty plea is truly knowing, intelligent, and voluntary are fairly stringent both in federal and state courts. See, e.g., Fed.R.Crim.P. 11(c), (d) (delineating the steps a federal court must take to ensure that a guilty plea is knowing and truly voluntary); Boykin v. Alabama, 395 U.S. 238, 89 S.Ct. 1709, 23 L.Ed.2d 274 (1969) (<HOLDING>). The Ninth Circuit has refused, however, to
holding that due process requires state courts to make an affirmative showing that a guilty plea is intelligent and voluntary holding that a guilty plea must be both knowing and voluntary and must be a voluntary and intelligent choice among the alternative courses of action available to a defendant holding that for a trial judge to accept a defendants guilty plea without an affirmative showing that it was intelligent and voluntary violates the defendants constitutional rights holding that a voluntary and intelligent plea of guilty is an admission of all the elements of a formal criminal charge holding that factual basis inquiry is one way of satisfying the constitutional requirement that a guilty plea be voluntary and intelligent but it is not mandated by due process