In Boykin v. Alabama (1969), 395 U.S. 238, the United States Supreme Court determined that a defendant who pled guilty could attack the ensuing conviction on the ground the record did not affirmatively establish a knowing and intelligent waiver of certain constitutional rights--the right to a jury trial, the right to confront witnesses, and the privilege against self-incrimination. (Id. at pp. 243-244 [89 S. Ct. at pp. 1712-1713].) Just months later, the California Supreme Court addressed the same issue in In re Tahl (1969), 1 Cal. 3d 122. Again, the defendant alleged his guilty plea was not made voluntarily or with a complete understanding of its consequences. The Tahl court, bound by Boykin, set forth the additional requirement that the record clearly state that the defendant specifically and expressly waived each of the three enumerated constitutional rights. (Id. at p. 132.) Both Tahl and Boykin involved direct challenges on an appeal from the contested conviction.