In some custody disputes parents are equally fit, other factors are not decisive, shared custody is ruled out, and the parental conflict is the only threat to children's well‐being. There are no systematic principles to resolve these disputes. To fill this gap, I introduce the equality principle. Following splitting the difference and goal‐setting theory, parents renegotiate under threat of randomization. If renegotiation fails, their chances of winning are equal. This principle may improve children's well‐being, parental behavior, court efficiency, and custody investigations. The principle is discussed in terms of child perspective, appellate rights, applicability, irrationality, and attorney effects on negotiations.