A Massachusetts courtroom is confronting one of the most difficult questions the criminal justice system can face: What happens when there is little dispute over who killed three children, but enormous disagreement over whether their mother was legally responsible for doing it? Lindsay Clancy, a 36-year-old former labor-and-delivery nurse from Duxbury, Massachusetts, is on trial for the January 2023 deaths of her three children — 5-year-old Cora, 3-year-old Dawson and 8-month