There was pending bill, Senate No. 2021, entitled, 'An Act relative to the consideration of domestic violence in custody and visitation proceedings.' A copy of the bill was transmitted with the order. The order recites: '[Senate No. 2021] would establish a presumption against awarding custody of a child to a parent under some circumstances; and . . . would further require that, upon reaching a finding by a preponderance of the evidence [that a parent has engaged in a pattern or serious incident of abuse], the burden of proof shifts to the challenged parent to prove that it is in the best interest of a child to be placed with such parent.' The legislature asked for an advisory opinion about the constitutionality of the bill.