Prenuptial agreements by their nature may not be equitable in the same sense as separation agreement entered into upon a divorce. Massachusetts law as interpreted by its courts holds that one spouse relinquishing claims to the existing assets of a future spouse – even if those assets are substantial – does not necessarily mean that a prenuptial agreement is invalid on its face.

Thus, it is possible for a prenuptial agreement to be one-sided in nature, and to leave one spouse in a position after the divorce that may be less than what he or she had during the marriage. Instead, the legal test of the conscionability of such an agreement is whether it strips the spouse contesting its validity of substantially all marital interests. The considerations underlying conscionability include whether either party to the prenuptial agreement engaged in fraud, or failed to fully and fairly disclose assets, or in some other way took unfair advantage the other at the time the agreement was executed.

For many years courts in Massachusetts used the term “fair and reasonable” to describe the requirement that a prenuptial agreement should be fundamentally fair even if it is not as balanced as a separation agreement might be, but they now use the term “conscionability” instead.

The drafting of a valid, conscionable prenuptial agreement, particularly when the prospective spouses are significantly unequal in the income and assets that they bring into the marriage, can be fraught with legal peril if it is done in a way that causes a court to conclude that it is not conscionable when executed. If a court finds unconscionability, the law will allow a judge to take a “second look” at the agreement with an eye toward changing its terms. Having an experienced family law attorney involved in the construction of a prenuptial agreement can help to avoid this undesirable outcome.