their disease, realizing that in such cases medicine is powerless.?_ -Hippocrates Medical futility concepts can be divided into two perspectives, retrospective or post-hoc futility and prospective or predictive futility. In post-hoc futility, treatment has failed to be curative. We see retrospectively that a treatment that perhaps held out some hope has proven to be futile. Post-hoc futility is not to be used for those who want a reason not to attempt a treatment. In other words, just because a treatment has failed for one patient does not mean it will necessarily fail for another, therefore the treatment cannot be considered to be futile, in all cases (Walker, 2011). Prospective or predictive futility, on the other hand, involves predicting that a treatment will be futile and therefore should not be attempted. Predictive futility is divided into several types: conceptual futility, probabilistic futility, physiologic futility, and doctor-patient goal disagreements. Conceptual futility is futility based on a particular concept or definition, an example is brain death. The medical legal concept of death holds that ventilator-dependent patients who have suffered "irreversible cessation of all functions of the entire brain including the brain stem" are dead. A In such cases, the ventilator is by definition a futile intervention because it cannot bring the patient back to life. In these cases, the law would allow physicians to discontinue the ventilator without family permission. In practice, however, despite the fact that continued artificial ventilation is futile, time is usually given to the family to come to terms