Possible impeachment evidence is not “material” under Brady v. Maryland (1963) 373 U.S. 83 unless the witness to be impeached supplied the only evidence linking the defendant to the crime. In this shaken baby case resulting in a second degree murder conviction, the defendant filed a habeas petition alleging that the district attorney had suppressed evidence that an expert witness had changed his testimony in another case involving similar facts. The Court of Appeal had issued the writ, but the Supreme Court reversed the order. The Court first outlined the standard of review applicable to Brady claims, noting that such mixed questions of law and fact were subject to independent review, although the factual findings of the referee were entitled to great weight. The Court then declined to consider whether the evidence, which had been mentioned in news reports, had actually been suppressed, because it was not necessary to reach that issue since the evidence was not material under Brady. Multiple witnesses connected the defendant to the crime, and one other expert corroborated the timeline of the child’s death. Further, it was unlikely that the impeachment evidence would have significantly undermined the witness’s testimony, and thus the defendant failed to establish the materiality element necessary for a Brady claim.