MA S1157

Replaces existing custody terminology with new definitions: "shared decision-making responsibility" (joint major decisions on education, healthcare, religion), "sole decision-making responsibility" (one parent decides), "shared residential responsibility" (child resides with both parents), and "primary residential responsibility" (child resides mainly with one parent)

Establishes temporary shared legal custody as the default upon filing a divorce or custody action, absent emergency conditions, abuse, or neglect; creates no presumption for or against shared arrangements at trial

Requires parties seeking shared custody to submit detailed parenting plans covering education, healthcare, dispute resolution procedures, and scheduling of parenting time including holidays and vacations

Mandates courts consider specific "best interest" factors including: parent-child relationship history, child's adjustment to home/school/community, each parent's ability to foster relationship with other parent, substance abuse concerns, domestic violence history, and child's preference if mature enough

Requires written court findings when ordering shared custody despite an existing abuse prevention order, and when considering additional factors beyond those enumerated in the statute