Who Gets To Decide When To End Life Support?

Bobbi Kristina Brown, daughter of the late Whitney Houston, is on life support after being found unconscious in her Georgia home. As the media speculates over her condition, who should get to decide when to take a patient off life support?  



This 16 minute HuffPost video provides a nice analysis.  They used high quality guest experts like Alan Meisel (law, ethics) and Randy Curtis (critical care medicine, ethics).