So, what is a sunset clause? By definition, it means that after a defined period of time, the clause has no effect. In a prenup, a sunset clause can take different forms but usually refers to voiding the agreement or only certain terms of the agreement after a period of time. In some cases, certain terms are actually expanded. Whether or not it’s right for you is clearly something that the two of you need to decide. If you would like more information about mediation, prenups and family law, check out my website — ClarePiroMediation.com.