A friend and I were discussing this recently. A friend of her family decided on assisted suicide due to incurable cancer but she did not discuss nor advise her family and friends about her decision. She did call friends on Monday to ask them to sing at her memorial on Friday, announcing only that she would be passing on Tuesday. Friends and family were shocked and devastated, but I do understand why she may have decided to avoid pleas and bargaining from others to wait. On the other hand, this woman had also lost her husband and mother to cancer within the previous two years, so was her decision entirely untainted by her recent losses?
I think this is a decision that needs to be thought out and discussed well in advance, not left to the last minute, perhaps made under emotional duress and/or sprung on family and friends. I have already let my kids know that assisted suicide is definitely an option for me under some circumstances and at some point I plan on written directives to support them and myself as needed.
If one is suffering a terminal disease, it can be relatively straightforward to decide when to pull the plug. But dementia is much trickier, since quality of life is determined subjectively and for a time dementia allows some quality of life interspersed with nothingness. Does one decide that being aware and responsive 20% or 10% or 1% of the time is worth the time spent otherwise? If one ultimately decides to leave the decision in someone else's hands is that fair to them?
So much of this is based on one's personal beliefs and their relationships that making a law that will effectively address all scenarios seems very difficult. I think the widest latitude combined with the best safeguards is needed. One safeguard could be that the individual has to choose, well ahead of time, who should make the decision, that it should be a minimum of three people and that at least one should have nothing to gain through the death of the individual. Another could be a significant waiting period for a person that is not suffering from dementia, so that a temporary sense of hopelessness does not lead to a hasty and permanent decision.
I don't think addictions or depression should be included under the "assisted suicide" banner. I spent much of my adult life wishing for a way to end the pain I felt, but now I am glad my attempts failed. I also know of people who spent decades addicted and/or in jail but are now functioning, productive and happy members of our society. In my opinion, assisted suicide should only be for physical ailments that are terminal according to our best medical knowledge today.