The determination and pronouncement of when a person has died has medical, ethical, and legal implications. Laws vary from state to state, and death is usually defined in a state’s statutes.

Definitions and terminology may vary from state to state but generally a person is dead when, according to ordinary standards of medical practice, there is irreversible cessation of the person's spontaneous respiratory and circulatory functions. If artificial means of support preclude a determination that a person's spontaneous respiratory and circulatory functions have ceased, the person is dead when, in the announced opinion of a physician, according to ordinary standards of medical practice, there is irreversible cessation of all spontaneous brain function.

Death occurs when the relevant functions cease. But a formal pronouncement of death is not a legal determination of the cause, manner, or time of death.

In Nebraska, the determination of death is governed by state statutes which align with the general medical and legal standards for defining death. According to Nebraska Revised Statute 71-1,219, a person is considered dead if they have sustained either an irreversible cessation of circulatory and respiratory functions, or an irreversible cessation of all functions of the entire brain, including the brain stem, as determined by accepted medical standards. The statute specifies that this determination must be made by a licensed physician. The pronouncement of death is a medical determination that a person has died, which is distinct from a legal determination of the cause, manner, or time of death. The formal pronouncement of death is necessary for legal purposes, such as issuing a death certificate and for the disposition of the body, but it does not itself establish the forensic details of the death.