Legal Definition of Death: The end of life. Most states legally define death as either the irreversible cessation of (a) brain function (brain death), or (b) circulatory and respiratory function | Learn about the legal definition of death and its importance in medical, legal, and ethical considerations. This comprehensive guide explains brain death and circulatory/respiratory death, as well as their implications in medical decision-making, organ donation, end-of-life care, and legal/ethical considerations. Gain a clear understanding of the legal boundaries surrounding death and make informed choices that respect the dignity of individuals