There is no set definition of joint physical custody. Many people think that joint custody automatically means that each parent has an equal amount of time, but that is not necessarily the case. Joint custody can refer to a number of different custody arrangements under which the parents share custody of the children. A "50/50" schedule is simply one form of a joint custody schedule, under which each parent has the same number of overnights.
Many factors have contributed to the surge in popularity of 50/50 custody arrangements. One of the biggest factors is the increase in families where both parents work outside the home and an increase in "breadwinner moms." Working mothers are now the top earners in about forty percent of households with children. In situations where both parents are working, there is less reason to default to mom as the custodial parent.
Another big factor influencing joint physical custody arrangements is an explosion of psychological literature supporting the theory that custodial arrangements where children have roughly equal contact with both parents is better for children. While there has recently been a backlash against some of this research, the concept is something that continues to become more commonly accepted. Recent literature has indicated that 50/50 schedules work best in low-conflict divorce cases where the parents are able to communicate regularly and effectively.
At the same time, a growing social movement supporting father's rights has given an extra push to the popularity and acceptance of shared custody arrangements. Our society now recognizes that it is vitally important for children to have the involvement of both parents, and it is now socially acceptable for men to take on a variety of roles that were once only viewed as acceptable for women. Additionally, society's concept of "family" continues to evolve with the legalization of same sex marriage which makes traditional gender roles of "mom" and "dad" less important in the context of evaluating what custody arrangements are in a child's best interest.
