If a couple chooses to call off their wedding, who gets the engagement ring?
Generally, if the bride calls off the wedding and her ring was a gift from the groom, it's appropriate for her to return it. If the groom calls it off, the bride may still want to return the ring because she doesn't want to be reminded of their failed engagement. (If he was a real jerk, though, we can't argue against taking it to the pawnshop.) If the ring is a family heirloom, it should go back to the family it came from, regardless of why the wedding was canceled. If the couple bought the ring together, they need to decide what to do with it, as with any other joint purchases they've made. (Perhaps they can both take it to the pawnshop and split the earnings!)
As to whether the recipient (in most cases, the woman) is legally entitled to keep the ring, laws regarding this issue vary from state to state. Check with a lawyer who specializes in matrimonial matters before you pursue legal action.