Should those who attempt suicide be punished?
Should those who consent to be abused by another, or maimed or killed, be punished?
“But they agreed / consented / wanted their death / injury.”
You premise that an ultimate criterion for law is the will of the individual victim. That premise is anarchical and inherently nihilistic. It itself is premised on a denial of nature and nature’s end.
In all men so foolish as to will to be injured or killed, nature itself rebels against their will. Rather, they rebel against nature. For nature inclines towards its preservation in all things. Such an inclination naturally gives way to injury or death only for the sake of an equal or higher good. For instance, the fireman can risk his life to rescue a child. A man can cut off his leg if it is pinned under a tree, so as to save the rest of his life.
Now, the suicide and the masochist, each of them is a man divided. Qua inflicting the pain / wanting the pain, injury or death, such a man is wicked. Qua a member of the human race, whose nature flinches at such prospects, he is a victim. Thus, he is not at one with himself. His chosen action contradicts the tendency of his person according to nature. Therefore, he should not be treated as only one ‘subject’ of the law. He is, so to speak, two ‘subjects’ of the law. And the perpetrator must be punished so as to right the wrong against the victim.
Society can, and should, punish those who begin to undergo injury or murderous action willingly. Failure in principle to find grounds for such punishment indicates failure of law, as follows. Who deny that there is foundation for such punishment are, implicitly if unwittingly, denying the very orientation of nature to its preservation. They thereby uproot all criminal law from its foundation in nature and relegate all such law to the arbitrary decisions of man. Failure to find grounds to punish such, then, is to undercut the very grounding of law in nature and to throw its foundations to the whim of man and that to which he consents.
Such undercutting consequently becomes a grave threat to all society. Conversely, one bellwether of society is its legally codified or judicially practiced toleration, in principle, of willed victimization.