The Maryland Waiver of Service of Summons (AO 399) is a document that is filed with a court when a defendant in a civil lawsuit is waiving their right to be served with a summons. This document is used to notify the court that the defendant is aware of the lawsuit and is choosing to waive the service of the summons. There are three types of Maryland Waiver of Service of Summons (AO 399): Waiver of Service of Summons by Mail, Waiver of Service of Summons by Personal Service, and Waiver of Service of Summons by Publication. Waiver of Service of Summons by Mail requires the defendant to sign and return the waiver form to the plaintiff's attorney via mail. Waiver of Service of Summons by Personal Service requires the defendant to sign the waiver form in the presence of a court-appointed officer. Waiver of Service of Summons by Publication is used when a defendant cannot be located and requires the plaintiff to publish notice of the lawsuit in a newspaper.