The defendant in a lawsuit must be served (delivered) a summons or citation (an order from the court to appear and answer the lawsuit) and a copy of the lawsuit (1) to provide due process (fairness) by giving the defendant notice of the lawsuit and the opportunity to appear in court and defend the lawsuit; and (2) to give the court personal jurisdiction (authority) over the defendant.

In New Mexico, as in all states, the legal process requires that a defendant in a lawsuit be properly served with a summons or citation and a copy of the lawsuit. This is a fundamental aspect of due process, which ensures that the defendant is given fair notice of the legal action against them and the opportunity to appear in court to defend themselves. The service of process must be carried out in accordance with the rules set forth by the New Mexico Rules of Civil Procedure. These rules specify who may serve the documents (typically a sheriff, deputy sheriff, or a licensed process server), as well as the acceptable methods of service, such as personal delivery to the defendant or, under certain conditions, to someone of suitable age and discretion at the defendant's residence or place of business. Proper service of process is also necessary for the court to establish personal jurisdiction over the defendant, which is the court's authority to make legal decisions affecting the defendant. If a defendant is not properly served, they may challenge the court's jurisdiction, and the case may be dismissed or the service may have to be completed again.