Why is suicide a crime?

Which leads us to the question of why suicide is a crime. Not being anywhere close to being the smartest person in the world, I can only reproduce an excerpt from Cecil Adam's "The Straight Dope".

"Views on suicide have varied widely, both historically and culturally. Certain Asian societies not only haven't condemned suicide but have sometimes expected or even rewarded it--Japan is the obvious example, with its tradition of hara-kiri, but by no means the only one. Consider the Indian practice of suttee--before the British outlawed it in 1829, an average of 500 widows immolated themselves in their husbands' funeral pyres each year, and were often regarded as nearly divine for doing so.

The ancient Greeks and Romans tended to take a practical view of suicide. Most philosophers accepted that there were circumstances in which it was honorable--for example, to save the lives of others, or as a protest against tyranny. Judaism traditionally forbids self-destruction, but nonetheless many Jews continue to mythologize the mass suicide at Masada, where 960 are believed to have killed themselves rather than surrender to the Romans. Early Christians were even more ambivalent about suicide, as you might expect from followers of a religion founded on martyrdom. Virgins who preferred suicide to dishonor were also celebrated, and at least one, Saint Pelagia, was canonized. Islam alone among these three faiths has a clear scriptural ban on suicide, but as recent events have made plain, that hasn't prevented certain zealots from arriving at permissive interpretations thereof.

The Christian opposition to suicide hardened starting with fifth-century theologian Augustine of Hippo, who argued that offing yourself is never justifiable because it violates God's injunction "thou shalt not kill." Suicides were deemed to have committed a mortal sin and denied Christian burial. Church law influenced civil law, and by the tenth century suicide in England was considered not just a crime but a felony. English common law distinguished a suicide, who was by definition of unsound mind, from a felo-de-se or "evildoer against himself," who had coolly decided to end it all and thereby perpetrated an infamous crime. Such a person forfeited his entire estate to the crown. Furthermore his corpse was subjected to public indignities, such as being dragged through the streets and hung from the gallows, and was finally consigned to "ignominious burial," as the legal scholars put it--the favored method was beneath a crossroads with a stake driven through the body. Other European states established similar laws, apparently hoping they would serve as deterrents. As time went on the punishments lessened. By the 17th century an English suicide forfeited only personal property; his heirs could still get his real estate. But the basic notion of suicide as a crime wasn't swept away in France till the revolution, and in England it took even longer: ignominious burial wasn't abolished until 1823 nor property forfeiture till 1870, and the deed itself remained a crime (albeit only a misdemeanor, and a rarely prosecuted one at that) until 1961. In many jurisdictions you can still be prosecuted for helping someone kill himself, and assisted suicide remains a hotly debated topic not just in the UK but in much of the world.

In the U.S. suicide has never been treated as a crime nor punished by property forfeiture or ignominious burial. (Some states listed it on the books as a felony but imposed no penalty.) Curiously, as of 1963, six states still considered attempted suicide a crime--North and South Dakota, Washington, New Jersey, Nevada, and Oklahoma. Of course they didn't take matters as seriously as the Roman emperor Hadrian, who in 117 AD declared attempted suicide by soldiers a form of desertion and made it--no joke this time--a capital offense.

— Cecil Adams"