Davis v. State (Crim. App. 1994)
In Davis v. State, 872 S.W.2d 743 (Tex. Crim. App. 1994), the Court said that "simply because the excluded testimony is not the only evidence supporting a defensive theory does not mean that it is not crucial to such defensive theory." Id. at 746.
The Court held that the testimony of an excluded witness was crucial because it corroborated other evidence favorable to the defense that the jury would have been more inclined to believe had the excluded testimony been admitted. Ibid.