In Giles v. California, 554 U.S. 353 (2008), the defendant shot and killed his ex-girlfriend. The defendant claimed he acted in self-defense. The prosecution sought to introduce statements made by the victim to police officers three weeks before her death in connection with a domestic violence report. The trial court admitted the statements into evidence under a provision that permitted admission of out-of-court statements describing the infliction or threat of physical injury on a declarant when the declarant is unavailable to testify at trial and the prior statements are deemed trustworthy. The defendant was convicted of first degree murder. (Giles, supra, 128 S.Ct. at pp. 2681-2682.) The United States Supreme Court considered whether the theory of "forfeiture by wrongdoing" accepted by the California Supreme Court -- that is, that the defendant forfeited his right to confront a witness who was unavailable because he murdered the witness -- is a founding-era exception to the confrontation right. (Giles, supra, 128 S.Ct. at p. 2682.) Forfeiture by wrongdoing is an equitable doctrine based on the principle that "one who obtains the absence of a witness by wrongdoing forfeits the constitutional right to confrontation." (Davis v. Washington (2006) 547 U.S. 813, 833.) In Giles, the high court clarified that the forfeiture by wrongdoing exception applies only where the defendant "engages in conduct designed to prevent the witness from testifying." (Giles, supra, 128 S.Ct. at p. 2683.) For example, where the evidence indicates the defendant's motive for murder was "to isolate the victim and to stop her from reporting abuse to the authorities or cooperating with a criminal prosecution," her prior statements about domestic violence would be admissible under the forfeiture doctrine. (Id. at p. 2693.) It concluded that at common law "unconfronted testimony would not be admitted without a showing that the defendant intended to prevent a witness from testifying. In cases where the evidence suggested that the defendant had caused a person to be absent, but had not done so to prevent the person from testifying--as in the typical murder case involving accusatorial statements by the victim--the testimony was excluded unless it was confronted or fell within the dying-declaration exception." (Id. at p. 2684.) The court added that the rule propounded by the California Supreme Court was not recognized at common law and not established in American jurisprudence. (Id. at p. 2687.) The United States Supreme Court addressed the development and scope of the forfeiture by wrongdoing doctrine. The issue in Giles was whether a statement is admissible under the forfeiture by wrongdoing doctrine any time the defendant's wrongful act renders the witness unavailable, or whether "the exception applies only when the defendant engaged in conduct designed to prevent the witness from testifying." (Id. at p. 359.) The court concluded that the forfeiture by wrongdoing doctrine does contain a "purpose requirement" -- i.e., that its application depends on whether the defendant's wrongful act was intended to make the witness unavailable. (Id. at p. 361.) Under Giles, "forfeiture by wrongdoing is implicated not only when the defendant intends to prevent a witness from testifying in court but also when the defendant's efforts were designed to dissuade the witness from cooperating with the police or other law enforcement authorities." In sum, the defendant was on trial for the murder of his girlfriend. (People v. Giles, supra, at p. 837.) The prosecution offered into evidence the prior statement by the murder victim to an officer investigating a report of domestic violence involving the defendant and the victim. (Id. at p. 839.) The prior statement was offered to rebut the defendant's testimony that he acted in self-defense. Our state Supreme Court held that the defendant forfeited his right to confront the victim by killing her. (Id. at p. 840.) The court reasoned that the defendant's constitutional right of confrontation was not violated because it was the defendant's own wrongdoing that created his inability to confront the witness as to the prior out-of-court statement. (Id. at p. 850.) In reversing the decision, the United States Supreme Court held that, before the doctrine of "'forfeiture by wrongdoing'" could be applied, there must be some showing that the defendant engaged in the wrongdoing with the intent of causing the witness's absence. (Giles v. California, supra, at pp.366-369.)