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 Kansas, the determination of death is governed by state statutes which align with the medical and ethical standards commonly accepted. Under Kansas law, a person is legally declared dead if there is an irreversible cessation of spontaneous respiratory and circulatory functions, or, in cases where artificial life support is involved, an irreversible cessation of all brain functions, as determined by a physician. This definition is consistent with the Uniform Determination of Death Act, which has been adopted in some form by most states, including Kansas. The pronouncement of death itself is a medical action that confirms the cessation of vital functions and is distinct from the legal determination of the cause, manner, or time of death, which may be subject to further investigation or certification by medical examiners or coroners.