The bill proposes significant amendments to Massachusetts child custody law by replacing Chapter 209B with the Massachusetts Uniform Child Custody Jurisdiction and Enforcement Act. It introduces comprehensive definitions related to child custody, establishes jurisdictional guidelines emphasizing the child's home state, and outlines procedures for inter-state communication and emergency handling of custody situations. The bill ensures that Massachusetts courts maintain exclusive jurisdiction over custody determinations unless specific conditions are met, and it reinforces the rights of parents and custodians by mandating notice and opportunities to be heard in custody proceedings.

Additionally, the bill details procedures for enforcing child custody determinations from other states, allowing for the registration of such determinations and providing a framework for contesting them. It emphasizes the need for expedited enforcement and includes provisions for immediate custody orders in cases of imminent risk to a child. The legislation also clarifies the roles of law enforcement and prosecutors in custody matters and includes a severability clause to maintain the enforceability of remaining provisions if any part is invalidated. The act is set to take effect on December 31, 2025.