A lawsuit seeking a declaratory judgment—also known as a “deck action” (dec. action)—is a lawsuit that asks the court to determine the rights, status, or other legal relations of the parties when a controversy has arisen, but before a wrong has been committed. A declaratory judgment seeks to prevent further litigation, liability, and harm. Declaratory relief is not available to settle disputes already pending before a court. A declaratory judgment is improper if the relief requested is raised for the first time in an amended petition (lawsuit) and merely addresses the same issues as were raised in the original petition.

A declaratory judgment is often sought when there is a disagreement over the meaning or application of an insurance policy or other contract, or a deed, will, trust, lease, statute, or municipal ordinance.

In South Dakota, a declaratory judgment action, or 'dec action,' is a legal proceeding where a party seeks a court's determination on the legal rights, status, or other relations of the parties involved, typically when a controversy exists but no wrong has yet been committed. This type of action is designed to clarify legal obligations and prevent future litigation, liability, or harm. Under South Dakota law, declaratory relief is not intended to resolve disputes that are already in litigation. Furthermore, a declaratory judgment is not appropriate if it is requested through an amended petition that does not introduce new issues but rather addresses the same matters as the original petition. Declaratory judgments are commonly used in cases involving uncertainties in contracts, insurance policies, deeds, wills, trusts, leases, statutes, or municipal ordinances, where parties seek to understand their rights and obligations before any breach occurs.