One of the biggest issues with lottery winnings is when one partner wins a big lottery after the couple has separated, but before the divorce is finalized. Obviously, the spouse who purchased the lottery ticket wants to keep all the winnings, while the other spouse wants a portion of the payout.
The rule, in most states, is that if the winnings came from a ticket purchased during the marriage, regardless of if the couple was separated or not, the winnings are marital or community property, and consequently can be divided between the husband and wife. In some states, however, the winner may keep all if the parties had already separated. An attorney from your area will be able to tell you how your state deals with lottery winnings.