that's the glue on the wicket: if someone hasn't made the decision by the time they lose capacity are they doomed to suffer? also, how do we determine exactly how much loss of mental function has to occur before someone loses the capacity to make this decision? Who gets to decide? The government doesn't have an interest but is also going to have to try to make a one-size-fits-all determination of mental function that will almost certainly be at least a little bit wrong for every specific case. The family, assuming there is one, knows the individual more personally and can speak to what they would want but might also have an interest in killing someone off prematurely in order to get an inheritance or be rid of a financial burden.