In State v. Yancey, the Supreme Court held, in a unanimous opinion by Chief Justice Nakamura, that a criminal defendant need not expressly state “I am guilty” or “I plead guilty” in open court to enter a valid guilty plea.
The Court said that although the best practice is to ask the defendant if he or she “pleads guilty,” the validity of the guilty plea is evaluated in light of the totality of the circumstances. Here, the defendant signed plea agreements stating that he “agrees to plead guilty.” The agreements explained the rights he was giving up by doing so. At the hearing, he acknowledged that he understood the agreements, that he was giving up important rights, and he agreed that the State had evidence to prove his guilt.
You can listen to the oral argument here.