Petitioner’s fundamental right to notice of the nature of the accusations against him was violated when the jury was instructed on aiding and abetting liability even though the prosecution gave no prior indication that it was pursuing this theory. Smith was charged with and convicted of the 2005 murder of his wife. Both before and during trial, the prosecution’s theory was that Smith directly perpetrated the murder. Smith’s defense was that he had an alibi for the time of the murder and, regardless, he was physically incapable of committing the murder. During the jury instructions conference, the prosecution requested an instruction on aiding and abetting, even though it had provided no evidence to support it. Over Smith’s objection, the judge ordered the instruction, believing he had a sua sponte duty to do so and noting that the evidence was closely balanced. Following the lunch recess, closing arguments began and the prosecution did not raise this new theory until its rebuttal. Smith was ultimately unsuccessful in his California state court review proceedings and he filed a habeas petition in the federal district court, arguing that the aiding and abetting instruction violated his constitutional right to adequate notice. The petition was granted and the Ninth Circuit affirmed. Under the Sixth Amendment and due process principles, a defendant has a fundamental right to be informed of the nature and cause of accusations against him so that he has an opportunity to prepare an adequate defense against every issue raised by the accusations. Under the circumstances of this case, Smith did not receive adequate notice that the prosecution would rely on an aiding and abetting theory of liability for first degree murder. The prosecution “ambushed” Smith and denied him a meaningful opportunity to prepare a defense when it requested the aiding and abetting instruction just before closing argument because the prosecution’s prior conduct affirmatively led Smith to believe that it would not rely on this theory of liability. The constitutional violation was not harmless under Brecht v. Abrahamson (1993) 507 U.S. 619, 623. Habeas relief was available under AEDPA because the California Court of Appeal’s decision on this issue was “based on an unreasonable determination of the facts” in light of the record.