 In addition, some policies that differentiate based on sex may be perceived as just or as beneficial to women. Affirmative action policies designed to root out the lingering effects of prior discrimination are an example of policies differentiating on the basis of sex that may be regarded as just. Other policies have been seen justified on a variety of grounds, including benefits to society, benefits to women, or distributive justice. In the US, these have included excluding women from jury duty based on their supposed responsibilities in the home, giving survivor’s benefits to widows but not to widowers, and creating single-sex schools. To some critics, all of these policies violate formal equality. To feminists, underlying issues for achieving equality include determining whether any of these policies enforce stereotypes, entrench prejudice, or treat anyone unfairly—and whether law should be used to challenge them as a result.