A few caveats about prenuptial agreements are in order. While some dimensions of marriage are off limits (child support, for example), care must be taken in the execution of a prenuptial agreement. While UPAA "makes it harder to contest a premarital agreement, [l]aws in other states vary significantly." Generally, however, successful challenges of prenuptials happen when a spouses proves unconscionability, coercion, or incomplete disclosure of assets.

Spouses have contested agreements they claimed they signed under duress. In particular that means that the signing spouse must have time to consider the rights she is giving up. In other words, a prenup signed the day of wedding is more likely to be challenged that one signed three months in advance. According to Frederic Siegel of Fitzmaurice and Siegel of Stanford, Connecticut, "some couples actually videotape the signing of the document, so if the prenup is challenged, there’s evidence both sides knew what they were doing." Even under UPAA, "a prenuptial agreement must been signed and entered into voluntarily." Lawyers are very creative in arguing coercion or duress. "For example, once invitations are sent, it can be argued that a spouse’s insistence on a prenup puts the other party in the position of either accepting the agreement or facing the embarrassment of canceling their wedding." Duress is a dimension of fairness. Fairness includes, not only sufficient time to consider the ramifications of the prenuptial agreement, but also time to consult an independent attorney for a legal opinion. Both parties must completely disclose all of their assets.