Members of the fathers' rights movement campaign for the reform of child support guidelines, which in most Western countries are based on maintaining the children's standard of living after separation, and on the assumption that the children live with one parent and never with the other. Activists state that the current guidelines are arbitrary, provide mothers with financial incentives to divorce, and leave fathers with little discretionary income to enjoy with the children during their parenting time. In the US, fathers' rights activists propose guidelines based on a Cost Shares model, in which child support would be based on the average income of the parents and the estimated child costs incurred by both parents. Laura W. Morgan has stated that it focuses on the relative living standards of divorcing parents rather than the best interests of the children and financially supporting them at the same level after divorce.