domicile for diversity purposes. Rodríguez-Díaz, 853 F.2d at 1030, 1033. Typically, “relevant rules of state law provide the basis for the applicable federal common law.” Id. at 1033. In Massachusetts, the domicile of a child is the same as the domicile of the parent who has lawful custody of the child. Durfee v. Durfee, 293 Mass. 472, 478, 200 N.E. 395 (1936) (emphasis added); see also Gil v. Servizio, 375 Mass. 186, 189, 375 N.E.2d 716 (1978) (“The domicile of the ... children [is] the same as the domicile of their parent who has lawful custody of them.”). Accordingly, a parent without lawful custody has “no power to change the domicile of his child while ... subject to a valid decree giving custody to the” other parent. Conley v. Conley, 324 Mass. 530, 534, 87 N.E.2d 153 (1949) (<HOLDING>). Bower was awarded sole legal custody of his
recognizing duty of parent to control conduct of child holding that the domicile of the child follows that of the parent with lawful custody holding that where interference with visitation becomes so pervasive as to harm the childs close relationship with the noncustodial parent there can be a conclusion drawn that the actions of the custodial parent show a disregard for the best interests of the child warranting a change of custody holding that a parent has a right of custody by reason of that parents ne exeat right the authority to consent before the other parent may take the child to another country recognizing that the child custody act required that the natural parent presumption must be seriously considered and heavily weighted in favor of the parent but that the presumption is rebutted if the clear and convincing evidence establishes that the best interest of the child is served by awarding custody to the third party