When are you dead? It's not an easy question to answer.
In fact, of the two great certainties in life, death and taxes, the former is actually harder to work out than the latter.
One way to define death is to look for behaviors and organs that have stopped working. But that doesn't necessarily mean someone is dead. The heart can stop temporarily and start up again. The body may be completely unresponsive but revive later. There are thousands of accounts of people "coming back to life" after being wrongly pronounced dead or, worse, buried alive.