[Latin, To the loss.] The clause in a complaint that sets a maximum amount of money that the plaintiff can recover under a default judgment if the defendant fails to appear in court.
It is a fundamental principle of due process that a defendant must be given fair notice of what is demanded of him or her. In a civil action, a plaintiff must include in the complaint served on a defendant a clause that states the amount of the loss or the amount of money damages claimed in the case. This clause is the ad damnum. It tells a defendant how much he or she stands to lose in the case.
In some states, the ad damnum sets an absolute limit on the amount of damages recoverable in the case, regardless of how much loss the plaintiff is able to prove at trial. The reason for this rule is that a defendant should not be exposed to greater liability than the ad damnum just because he or she comes into court and defends himself or herself. In states that follow this rule, a plaintiff may be given leave to increase the amount demanded by amending the complaint if later circumstances can be shown to warrant this. For example, a plaintiff who sues for $5,000 for a broken leg may find out after the action has begun that she will be permanently disabled. At that point, the court may allow the plaintiff to amend her complaint and demand damages of $50,000.
In most states and in the federal courts, a plaintiff can collect money damages in excess of the ad damnum if proof can be made at trial to support the higher amount. A defendant may ask for more time to prepare the case in order not to be prejudiced at trial if it begins to look as though the plaintiff is claiming more money than the ad damnum demands. However, the defendant cannot prevent judgment for a higher amount.
AD DAMNUM, pleading. To the damage. In all personal and mixed actions, with the exception of actions of debt qui tam, where the plaintiff has sustained no damages, the declaration concludes ad damnum. Archb. Civ. Pl. 169.