The Court of Appeal’s ruling that the trial court’s curtailment of petitioner’s cross-examination of the victim did not violate his Sixth Amendment right to confrontation was objectively unreasonable. Petitioner Ortiz was convicted by a jury of willful infliction of corporal injury to his wife, Miriam (Pen. Code, § 273.5). At trial, Miriam reluctantly testified that Ortiz had punched and kicked her, which was consistent with a statement she previously gave police. During the cross-examination of Miriam, the trial court precluded the defense from asking her whether she was afraid to deviate from her previous statement incriminating Ortiz because of threats allegedly made against her by the prosecutor. The California Court of Appeal implicitly rejected Ortiz’s constitutional claim in his direct appeal that the trial court violated his Sixth Amendment right to confront adverse witnesses when it prohibited him from cross-examining Miriam regarding the alleged threat. The federal district court denied Ortiz’s habeas petition raising this issue. The Ninth Circuit reversed. The trial court’s restriction on Ortiz’s cross-examination of Miriam was an objectively unreasonable application of Michigan v. Lucas (1991) 500 U.S. 145, which held that restrictions on a criminal defendant’s right to confront witnesses may not be arbitrary or disproportionate to the purposes they are designed to serve. Here, the jury may have questioned Miriam’s credibility if Ortiz had been permitted to elicit testimony that she was afraid to deviate from her original statement. As the victim and sole eyewitness, Miriam’s motive for testifying bore directly on the likelihood that the jury would credit essential testimony by the primary witness. The jury had no reason to question Miriam’s reasons for testifying without hearing testimony concerning the alleged threats. The trial court’s complete exclusion of this relevant testimony was disproportionate to any conceivable valid purpose. Applying the factors set forth in Delaware v. Van Arsdall (1986) 475 U.S. 673, 684, the court concluded that the trial court’s violation of Ortiz’s right to confrontation had a substantial and injurious effect on the jury’s verdict and was not harmless.