HOMICIDE, in law, is the act of killing a human being, whether such act be criminal or not. Blackstone distin-guishes three kinds of homicide—(1) justifiable, (2) excus-able, and (3) felonious.

The most important case of justifiable homicide is the execution of a criminal in due course of public justice. This condition is most stringently interpreted. " To kill the greatest of malefactors deliberately, uncompelled, and extra-judicially is murder. . . . And further, if judgment of death be given by a judge not authorized by lawful com-mission, and execution is done accordingly, the judge is guilty of murder" (Stephen's Commentaries, book vi. c. iv.). The execution must be carried out by the proper officer or his deputy : any person executing the sentence without such authority, were it the judge himself, would be guilty of murder. And the sentence must be strictly pursued : to execute a criminal by a kind of death other than that to which he has been judicially condemned is murder.

Homicide committed by an officer of justice in the course of carrying out his duty, as such, is also justifiable ; e.g., where a person resists a legal arrest and is killed in the struggle ; where officers in dispersing a riotous assemblage kill any of the mob, &c. In these cases the homicide must be shown to have been absolutely necessary. Again, homicide committed for the prevention of forcible and heinous crime, such as violent robbery, or murder, or house-breaking during the night, is justifiable.

Excusable homicide is homicide committed either by misadventure or in self-defence. In the former case, where a man in the course of doing some lawful work, accidentally and without intention kills another, the homicide is excused ; e.g., shooting at a mark and undesignedly hitting and kill-ing a man. The act must be strictly lawful, and death by misadventure in unlawful sports is not a case of excusable homicide. Homicide in self-defence is excusable when the slayer is himself in immediate danger of death, and has done all he could to avoid the assault. Accordingly, if he strikes and kills his assailant after the assault is over, this is not excusable homicide. And if the assault has been premeditated, as in the case of a duel, the death of either antagonist is murder, and not excusable homicide. The excuse of se defendendo covers the case in which a person in defence of others whom it is his duty to protect—children, wife, master, &c.—kills an assailant. It has been con-sidered doubtful whether the plea of self-defence is avail-able to one who has himself provoked a fray, in the course of which he is so pressed by his antagonist that his only resource is to kill him.

The distinction between excusable and justifiable homi-cides refers back to a period in the history of the law when the former were considered to carry with them some taint of guilt, and to require some kind of punishment or expia-tion. In early law homicide, however innocent, subjects the slayer to the lawful vengeance of the kindred of the dead man. We have a good example of this feeling in the Jewish institution of cities of refuge, to which innocent manslayers might flee from the avenger of blood. The case mentioned in Deut. xix. 5 is a typical instance of what we should call excusable homicide :—"A man goeth into the wood with his neighbour to hew wood, and his hand fetcheth a stroke with the axe to cut down the tree, and the head slippeth from the helve, and lighteth upon his neighbour, that he die." In English law, the same feeling long remained. Excusable homicide involved at least forfeiture of goods, which, however, might be recovered as a matter of course by the innocent criminal obtaining a pardon and writ of restitution. Afterwards judges appear to have been in the habit of directing an acquittal in such cases. It is only by a statute so recent as 9 Geo. IV. c. 31 that the innocence of excusable homicide is expressly declared.

Felonious homicide includes SUICIDE, MANSLAUGHTER, and MURDER—the law relating to which is discussed under the different headings. These distinctions of the English law correspond generally to those of other systems. The chief difficulty is the definition of murder—the distinction between the highest and second degree of criminal homi-cide. In English law the element of malice aforethought chiefly distinguishes murder from manslaughter. In Scot-land the term culpable homicide is the equivalent of the manslaughter of English law.