A premarital or prenuptial agreement—also known as a prenup—is an agreement between prospective spouses made in contemplation of marriage and is effective on marriage. A premarital agreement must be in writing and signed by both parties.

Laws vary from state to state, but the rights and obligations the parties may agree to in a premarital agreement may include:

• the rights and obligations of each of the parties in any of the property of either or both of them whenever and wherever acquired or located;

• the right to buy, sell, use, transfer, exchange, abandon, lease, consume, expend, assign, create a security interest in, mortgage, encumber, dispose of, or otherwise manage and control property;

• the disposition of property on separation, marital dissolution, death, or the occurrence or nonoccurrence of any other event;

• the modification or elimination of spousal support or alimony;

• the making of a will, trust, or other arrangement to carry out the provisions of the agreement;

• the ownership rights in and disposition of the death benefit from a life insurance policy;

• the choice of law governing the construction and interpretation of the agreement; and

• any other matter, including their personal rights and obligations, not in violation of public policy or a statute imposing a criminal penalty.

Child Support May Not Be Adversely Affected by a Premarital Agreement

The right of a child to support may not be adversely affected by a premarital agreement.

Reasons A Premarital Agreement May Be Unenforceable

A premarital agreement is not enforceable if the party against whom enforcement is requested proves that:

• the party did not sign the agreement voluntarily; or

• the agreement was unconscionable when it was signed and, before signing the agreement, that party: (1) was not provided a fair and reasonable disclosure of the property or financial obligations of the other party; (2) did not voluntarily and expressly waive (in writing) any right to disclosure of the property or financial obligations of the other party beyond the disclosure provided; and (3) did not have and could not reasonably have had adequate knowledge of the property or financial obligations of the other party.

A question of unconscionability of a premarital agreement is usually decided by the court as a matter of law rather than by the jury as a matter of fact.

Law is Often Located in State Statutes

In many states the law regarding premarital or prenuptial agreements is located in the state’s statutes—often in the family code or domestic relations code.

In South Dakota, a prenuptial agreement, also known as a premarital agreement, is recognized and enforceable as per state statutes. These agreements allow future spouses to determine in advance how their property will be managed and controlled during the marriage and how it will be divided upon separation, divorce, or death. The agreements can also address financial rights and obligations but cannot adversely affect child support obligations, as child support is determined based on the best interests of the child. Prenuptial agreements in South Dakota must not include terms that violate public policy or criminal laws. For a prenuptial agreement to be enforceable, it must be entered into voluntarily by both parties, and there must be a fair and reasonable disclosure of the financial assets and obligations of each party. If a party did not have, or reasonably could not have had, an adequate knowledge of the other party's finances, the agreement may be considered unconscionable and thus subject to challenge in court. The enforceability of a prenuptial agreement is ultimately determined by the courts, which will assess whether the agreement was signed under duress, without proper disclosure, or if it is unconscionable at the time of enforcement.