Uniform Simultaneous Death Act
  
Sounds like the kind of thing they had at Jonestown. But no, it's an inheritance law dealing with situations where two or more people die at the same time.
You and your spouse are driving together on a motorcycle. You turn a corner too quickly and run directly into a moose standing in the middle of the road. You're decapitated instantly when your head hits the moose's rib cage. Your spouse just has severe internal bleeding, but dies a few hours later when the moose steps on her spleen. Neither of you have a will. Both you and your spouse had kids from a previous marriage. They hate each other. Happy family. Good times.
Theoretically, the inheritance could work like this: since you died first, your assets get inherited by your spouse, who holds on for a few hours and then dies herself. Then her kid from the previous marriage would get everything. Your kid gets nothing, since everything flows first to her estate and then to her heirs.
The Uniform Simultaneous Death Act circumvents this. It sets a 120-hour limit. If people are killed in the same event, though not dying at precisely the same time, their estates are combined and distributed equally among everyone's relatives. Both your kids and your spouse's kids get an equal share, instead of following a weird string of estate dominoes.