Kristine and Lisa were lesbian partners who obtained a declaration in family court that Lisa was the second parent of the child Kristine was carrying. The court’s stipulated judgment was that both parents would have joint custody. When the child was two years old, the couple separated, and Kristine moved to set aside the judgment. The trial court ruled for Lisa, but the Court of Appeal reversed, finding that the family court could not declare parentage based on a stipulation. The California Supreme Court reversed the appellate court, finding that it need not decide whether the stipulated judgment was valid because Kristine was estopped from challenging its validity. The trial court had jurisdiction because Kristine invoked it to determine the parentage of her child. She stipulated to naming Lisa as the other parent, and coparented with her for two years. It would be unfair to Lisa and the child to permit her to challenge the validity of the judgment. It would also contravene public policy which favors two parents for a child rather than one.