The difference between suicide and homicide is that a person commits suicide by killing himself. A person commits homicide by killing another person. The law treats these acts the same in terms of making the acts unlawful. To do this, the law creates numerous classifications of homicide, because the circumstances surrounding the act of homicide may require different levels of punishment, or no punishment at all. While you cannot really impose punishment on a person who commits suicide, common law still makes suicide unlawful with unique consequences.
The law historically punished suicide by mutilation of the corpse. This occurred by burning the body and sometimes dragging the body through the streets. The law also either denied burial of a person who committed suicide or required burial to be in an isolated location in an unmarked grave. A person in England committing suicide would forfeit all of his property to the king, which prevented inheritance. Now, although suicide and homicide are generally unlawful, the primary purpose of making suicide illegal is not to impose punishment, but to impose professional help such as psychological treatment on those who attempt suicide but survive.
Suicide and homicide are both generally aggressive acts. In homicide, however, one person is acting to end someone else’s life. Accordingly, the law will punish a person who commits homicide when the circumstances require punishment. For instance, a majority of jurisdictions would not impose punishment on a person who kills another person in self-defense of his own life or while defending someone else’s life. In contrast, if a person is trying to rob a bank and kills a bank teller, then the law will punish the bank robber for committing homicide.
The circumstances behind the act of killing another person vary, so the common law created classifications of homicide. They are justifiable, excusable and criminal. Justifiable homicide means the law authorizes a person to kill in the circumstances presented, excusable homicide means there is a legal defense to the act of killing; and criminal homicide means the killing is unlawful. The classification system of homicide punishment is one more distinction between suicide and homicide. The law seeks proper punishment and deterrence for homicide; the law regarding suicide seeks to impose medical treatment, not punishment.
There is another connection between suicide and homicide, one that has inspired numerous studies. That connection is murder-suicide, in which a person will commit murder — a form of homicide — and then commit suicide. According to a 2012 study by The Violence Policy Center, murder-suicide mostly occurs at home, between people who have an intimate relationship, and children are often witnesses or victims. Statistics show that the perpetrator of the murder-suicide is usually a male.