A commenter on the breach of promise to marry thread raised the perennial question: When an engagement is broken, does the bride have a legal duty to return the engagement ring to the groom?
States divide into three camps on this. (I will assume the ring is given by the groom to the bride, but in principle the rules are sex-neutral.)
1. Many states conclude that an engagement ring, as a gift in contemplation of marriage, is conditional on the marriage taking place. If the marriage is called off, the bride must return the ring to the groom. See, e.g., Carroll v. Curry (Ill. App. 2009). No state, to my knowledge, strictly requires that she fling it at him, but it’s considered a nice touch under the right circumstances.
2. Many other states conclude that an engagement ring is generally a gift conditional on the marriage taking place, but that the bride must return the ring only if she and not the groom is the one “at fault” for the breakup. See, e.g., Clippard v. Pfefferkorn (Mo. App. 2005). What constitutes “fault” is not universally settled; some states apparently focus on just who called off the engagement, while others look to whether the person who called off the engagement had sufficient reason (which raises obvious problems).
3. At least one state, Montana, concludes that an engagement ring is an unconditional gift. See Albinger v. Harris (2002).
The majority rule is sometimes said to be rule 2, but I’m not sure that’s so; rule 1 might these days be dominant or at least tied. Rule 3 appears to be far behind.
All this is just the default: If the giver makes clear at the outset on what terms the ring is given, that would take precedence. But such care and precision would likely substantially diminish the likelihood that the marriage will actually take place.