What is Manslaughter?

Legal Definition
Manslaughter is a legal term for homicide considered by law as less culpable than murder. The distinction between murder and manslaughter is sometimes said to have first been made by the Ancient Athenian lawmaker Draco in the 7th century BCE.

The definition of manslaughter differs among legal jurisdictions.
-- Wikipedia
Legal Definition
Manslaughter is the act of killing another human being in a way that is less culpable than murder. See Homicide.

Under both the common law and the Pennsylvania Method of differentiating degrees of murder, manslaughter was divided into voluntary and involuntary manslaughter:
  • Voluntary manslaughter is intentionally killing another person in the heat of passion and in response to adequate provocation.
  • Involuntary manslaughter is negligently causing the death of another person.
Under the Model Penal Code, manslaughter includes:
  • Reckless homicide
  • Homicide that would be murder, but "is committed under the influence of extreme mental or emotional disturbance for which there is reasonable explanation or excuse."
See Model Penal Code § 210.3
Legal Definition
Crim. law. The unlawful killing of another without malice either express or implied. 4 Bl. Com. 190 1 Hale, P. C. 466. The distinctions between manslaughter and murder, consists in the following. In the former, though the act which occasions the death be unlawful, or likely to be attended with bodily mischief, yet the malice, either express or implied, which is the very essence of murder, is presumed to be wanting in manslaughter. 1 East, P. C. 218 Foster, 290.

2. It also differs from murder in this, that there can be no accessaries before the fact, there having been no time for premeditation. 1 Hale, P. C. 437; 1 Russ. Cr. 485. Manslaugbter is voluntary, when it happens upon a sudden heat; or involuntary, when it takes place in the commission of some unlawful act.

3. The cases of manslaughter may be classed as follows those which take place in consequence of, 1. Provocation. 2. Mutual combat. 3. Resistance to public officers, &c.

4. Killing in the prosecution of an unlawful or wanton act. 5. Killing in the prosecution of a lawful act, improperly performed, or performed without lawful authority.

4. - 1. The provocation which reduces the killing from murder to manslaughter is an answer to the presumption of malice which the law raises in every case of homicide; it is therefore no answer when express malice is proved. 1 Russ. Cr, 440; Foster, 132; 1 East, P. C. 239; and to be available the provocation must have been reasonable and recent, for no words or slight provocation will be sufficient, and if the party, has had time to cool, malice will be inferred.

5. - 2. In cases of mutual combat, it is generally manslaughter only when one of the parties is killed. When death ensues from duelling the rule is different, and such killing is murder.

6. - 3. The killing of an officer by resistance to him while acting under lawful authority is murder; but if the officer be acting under a void or illegal authority, or out of his jurisdiction, the killing is manslaughter, or excusable homicide, according to the circumstances of the case. 1 Moody, C. C. 80, 132; 1 Hale, P. C. 458; 1 East, P. C. 314; 2 Stark. N. P. C. 205; S. C. 3 E. C. L. R. 315.

7. - 4. Killing a person while doing an act of mere wantonness, is manslaughter as, if a person throws down stones in a coal-pit, by which a man is killed, although the offender was only a trespasser. Lewin, C. C. 179.

8. - 5. When death ensues from the performance of a lawful act, it may, in consequence of the negligence of the offender, amount to manslaughter. For instance, if the death has been, occasioned by negligent driving. 1 East, P. C. 263; 1 C. & P. 320 S. C. 9 E. C. L. R. 408; 6 C. & P. 629; S. C. 25 E. C. L. R. 569. Again, when death ensues, from the gross negligence of a medical or surgical practitioner, it is manslaughter. 1 Hale, P. C. 429; 3 C. & P. 632; S. C. 14 E, C. L. R. 495.
-- Bouviers Law Dictionary
Legal Definition
In criminal law. The unlawful killing of another without malice, either express or implied; which may be either voluntarily, upon a sudden heat, or involuntarily, but in the commission of some unlawful act 1 Hale, P. C. 466; 4 BL Comm. 191. Manslaughter is the unlawful killing of a human creature without malice, either express or implied, and without any mixture of deliberation whatever ; which may be voluntary, upon a sudden heat of passion, or involuntary, in the commission of an unlawful act, or a lawful act without due caution and circumspection. Code Ga. 1882, § 4324; Pen. Code Cal. § 192. And see Wallace v. U. S„ 162 U. S. 466, 16 Sup. Ct. 859, 40 L. Ed. 1039; Stokes v. State, 18 Ga. 35; Clarke v. State, 117 Ala. 1, 23 South. 671, 67 Am. St Rep. 157; U. S. v. King (C. C.) 34 Fed. 309; People v. Maine, 51 App. Div. 142, 64 N. Y. Supp. 579; High v. State, 26 Tex. App. 545, 10 S. W. 238, 8 Am. St Rep. 488; State v. Workman, 39 S. C. 151, 17 S. E. 694; State v. Brown, 2 Marv. (Del.) 380, 36 Atl. 458; U. S. v. Lewis (C. C.) Ill Fed. 632; State v. Zellers, 7 N. J. Law, 243. The distinction between "manslaughter" and "murder" consists in the following; In the former, though the act which occasions the death be unlawful or likely to be attended with bodily mischief, yet the malice, either express or implied, which is the very essence of murder, is presumed to be wanting in manslaughter. 1 East, P. C. 218; Comm. v. Webster, 5 Cush. Mass.) 304, 52 Am. Dec. 711. It also differs rom "murder" in this: that there can be no accessaries before the fact, there having been no time for premeditation. 1 Hale, P. C. 437; 1 Russ. Crimes, 485; 1 Bish. Crim. Law, 678. See Voluntary manslaughter.
-- Black's Law Dictionary
Legal Definition
The unlawful killing of a human being, without malice, express or implied. See 134 Am. St. Rep. 727, note.
-- Ballentine's Law Dictionary