FindLaw shows the traditional and the modern approaches to annulments based on allegations of fraud.
Joanna L. Grossman writes (excerpt):
In Part One of this series, I discussed the traditional approach to defining fraud as a ground for annulment, which requires that the misrepresentation relate to the “essentials of the marriage” – some aspect of marriage that is fundamentally important to any marriage, not just to the particular spouse seeking an annulment.
In this Part, I will argue that there has been at least a subtle shift in the doctrine in some jurisdictions away from this one-size-fits-all approach to a more individualized approach. Under this more modern approach, a court might ask whether a misrepresentation related to something that was fundamental to this marriage, rather than to marriage in general. This type of approach treats marriage more like other contracts – where private parties define the terms of the deal, as well as the circumstances under which they are willing to enter it at all.