Many people may read the question posed in our title and immediately think that it is impossible to invalidate a prenuptial agreement. This is because it has been ingrained, over many years, that prenups are rock-solid contracts that can't be challenged or changed. However, this is a myth. There are legitimate reasons why someone may challenge a prenup, and those reasons could lead to part or all of the prenup being invalidated.
One of the reasons why a prenup can be invalidated is because one of the spouses did not have appropriate time to consider or review the contract. This can happen because one spouse pressures the other to sign it, or if one spouse presents to his or her spouse with little time to consider it before their wedding day.
Another reason why a prenup may be invalidated is because of the provisions included in the contract. The provisions may contain illegal or invalid information, or the provisions may be incomplete or non-compliant.
Last but not least, the concept of "unconscionability" could undermine a prenup and lead to it being invalidated. Prenups are supposed to be "conscionable," which is to say that they are supposed to be fair to a certain degree. If the contract is so imbalanced that one spouse would suffer far more than the other in the wake of a divorce, then the prenup could be deemed "unconscionable" and, thus, be invalidated.
Source: FindLaw, "Top 10 Reasons a Premarital Agreement May be Invalid," Accessed Dec. 7, 2017