I have considered assisted suicide--or rather, I have thought about what I would do if it were legal in the United States, where I live--during some of the low points of my life.

Let's just say the patient doesn't have free will. So you decide not to follow the patient's request for assisted suicide. The patient is angry at you because... the patient has the free will to be so. Proof by contradiction.

Now let's say you argue that the patient has no choice but to do that (be angry at you because you denied death). Well then I can say that you have no choice but to argue that, meaning you don't have free will, and the notion of free will doesn't exist.

Since your argument relies on a non-falsifiable idea yet demands "proof" that the patient is incurable, it is irrational. Belief in a metaphysical idea such as free will is one thing, using it to determine whether a person has the right to assisted suicide is another.

I just don't believe doctors should be the gatekeepers to "assisted" suicide. If the patient doesn't make the determination as to whether to end their own life, it is no longer a suicide, but a mercy killing (whether mercy killings are a good idea is simply a separate argument). This is especially true in a medical setting, where the patient is not likely to push the button to end their life. Factually, it's just not a suicide anymore if it's the doctor doing it. Assisted suicide is just a false label at that point.

Let's say I was desperate enough to take the poison (as Socrates did rather for contrasting reasons, instead of compromising his morals, being instead uncompromising). I would not (in the present moment) find it only a disservice, but rather a crime against my rights as a free being to have my life unwillingly in the hands of another. I would nod my head, inwardly hating the same people who released me to death, since my fate is not in my hands, but theirs. In a sense, I am no longer a free person, but a slave to their judgement without a need for due process.

And further, how would one regulate such an industry? The doctors get paid to do the procedure--presumably well--and that creates a massive conflict of interest. The patient cannot come back from the dead to complain, and the family (if any) is given the documents signed by the patient. No one can make a claim for a wrongful death, since there is no way to prove that the doctors were wrong about the patient's desire for death and lack of cure, since the patient is dead!

In short, I think that assisted (or unassisted) suicide should either be totally legal and voluntary, or totally illegal. I prefer illegality, but I consider that an invalidated opinion.

Personally, I think the reason for its illegality (and many of the legalities, social norms, beliefs, etc for societies today) is simply utilitarian and a type of societal natural selection. Something about assisted suicide must have made societies weak in the past, so societies that did not allow it were naturally stronger than societies that did. Or maybe it's just happenstance (determined happenstance, that is). But today things are different, with mental illness on the rise alongside nihilism. Maybe we are being more open minded if we allow things like that.