At what point in time would you pull the plug on life support?

It would depend on the situation and the degree of illness/injury. Every situation is different. If there was no brain function and the body (not the person) was existing merely because a machine was breathing for them, feeding them, and essentially taking care of every function of a living person, I would seriously consider terminated life support. If life support was indeed "supporting life" and allowing someone to recuperate and/or regenerate from illness or injury (from an accident, for example) and the brain was still functioning at some capacity, I would continue the support, even if there was a chance the individual would never regain full functioning. Regardless of the circumstances, however, pain managment would be my number one concern and whether or not I decided to "pull the plug", the patient's comfort would be my first priority.

i wouldn't pull the plug at all. my dad was on life support till he breathed his last. the ventilator just stopped functioning when his heart said, hey, i've had enough. so, if it's time to go, you just have to go. even the machine will just stop on its own.