Just to be clear (and redundant), living wills and physician-assisted suicide, while both end-of-life issues, are separate concepts.
At this time, assisted suicide is out of the hands of physicians, considering that it's largely illegal. The most we can do is provide pain relief, which just so happens to hasten death in many instances. I guess we can call it ethical tap-dancing, but the hastened death is considered incidental to the primary goal of relief from suffering. Were it to become legal on a large scale, I would imagine many physicians would have a problem with it, seeing as it requires an act of commission that violates our first principle of primum non nocere.
Living wills are fantastic in principle and highly problematic in practice. For one, too few people actually have one. Secondly, they're woefully lacking in details. They often will decline things like "heroic measures" or "life support", but these are meaningless terms to a physician. The living will needs to include specifics, like do you want to be intubated? Do you want CPR? Mechanical ventililation? Do you want IV vasopressors? IV antibiotics? Palliative surgery? And this list goes on. In the absence of specific directives, the next of kin will almost always choose to do more rather than less, and physicians will go a long with it because no one want the liability of being accused of withholding care.
Lastly, living wills hold up right until the point that there is a family dispute. If the spouse is still in the picture, then it should theoretically be up to them, but adult children really muddy the water. And God forbid that the spouse is gone and there are multiple adult children. Invariably, there's the estranged daughter that lives a thousand miles away and didn't participate at all in end-of-life care who shows up at the 11th hour. That person always wants a full-court press and is appalled at her siblings for wanted to "pull the plug". And, in the absence of a POA, that daughter shares co-equal decision-making authority with the other siblings. No physician will withhold or withdraw care in that scenario.
Tl;dr: get a living will and make it detailed. Also get a medical power of attorney. But most importantly, speak with your family so that they understand your desires. Next of kin often won't follow your wishes, even if they're clearly outlined in the living will, if they're coming out of left field. Conversely, things are more likely to go smoothly with someone who has conveyed their wishes personally, even if those wishes are enumerated in a legal document.
