Assume that a California Superior Court relies on two different and independent reasons to reach a judgment. Then, the Court of Appeal affirms the judgment based on one of these reasons, but never bothers to mention the alternative ground. Can the ground that was ignored on appeal still have preclusive effect? Surprisingly, the answer probably depends on whether the preclusion question arises in state or federal court - even though California substantive preclusion rules are supposed to govern this issue regardless of the forum.