An annulment is a legal procedure within secular and religious legal systems for declaring a marriage null and void. Unlike divorce, it is usually retroactive, meaning that an annulled marriage is considered to be invalid from the beginning. In the canon law of the Catholic Church, an annulment is properly called a "Declaration of Nullity," because according to Catholic doctrine, the marriage of baptized persons is a sacrament and, once consummated and thereby confirmed, cannot be dissolved as long as the parties to it are alive. A "Declaration of Nullity" is not dissolution of a marriage, but merely the legal finding that a valid marriage was never contracted. An annulment can be sought for various reasons, such as inability to consent to marriage, lack of physical capacity to consummate the marriage, consent for the marriage obtained by force, duress, or fraud, and incurable mental illness for a period of five years or more. Each state has its own laws regarding grounds for marriage annulment, and the process and requirements may vary depending on the state of residence. An annulment is different from a divorce, as it erases the marriage from a legal perspective and declares that the marriage never existed, while a divorce legally ends a marriage that was once valid.