Conversely, such practices may be outlawed and penalized in parts of the world out of concerns of the infringement of women's rights, or the infringement of children's rights (both female and male children), and because of international law.In developed parts of the world, there has been a general trend towards ensuring equal rights within marriage for women and legally recognizing the marriages of interfaith, interracial, and same-sex couples.
For example, the number of marriages in Europe decreased by 30% from 1975 to 2005.
This forced Gough to disregard sexual access as a key element of marriage and to define it in terms of legitimacy of offspring alone: marriage is "a relationship established between a woman and one or more other persons, which provides a child born to the woman under circumstances not prohibited by the rules of relationship, is accorded full birth-status rights common to normal members of his society or social stratum." Economic anthropologist Duran Bell has criticized the legitimacy-based definition on the basis that some societies do not require marriage for legitimacy.
He argued that a legitimacy-based definition of marriage is circular in societies where illegitimacy has no other legal or social implications for a child other than the mother being unmarried.
Whom they marry may be influenced by socially determined rules of incest, prescriptive marriage rules, parental choice and individual desire.
In some areas of the world, arranged marriage, child marriage, polygamy, and sometimes forced marriage, may be practiced as a cultural tradition.