I am well aware that many definitions of "murder" stick "unlawful" in front it. The common law definition of murder did not include the adjective "unlawful". From
What is MURDER?
The crime committed where a person of sound mind and discretion (that is, of sufficient age to form and execute a criminal design and not legally “insane”) kills any human creature in being (excluding quick but unborn children) and in the
peace of the state or nation (including all persons except the military forces of the
public enemy in time of war or battle) without any warrant,
justification, or excuse in law. with malice aforethought, express or implied, that is, with a deliberate purpose or a design or
determination distinctly formed in the mind before the commission of the act, provided that death results from the injury Inflicted within one
year and a day after its infliction. See
Kilpatrick v. Com., 31 Pa. 19S;
Llotema v. U. S., 186 U. S. 413. 22 Sup. Ct 895, 46 L. Ed. 1225; Guiteau’s Case (D. C.) 10 Fed. 101;
Clarke v. State. 117 Ala. 1, 23 South. 071, 67 Am. St. I top. 157;
People v. Enoch, 13 Wend. (N. Y.) 167. 27 Am. Dec. 107;
Kent v. People, 8 Colo. 5(13. 9 Pac. 852;
Com. v. Webster, 5 Cush. (Mass.) 205. 52 Am. Dec. 711;
Armstrong v. State. 30 Fla. 170. 11 South. 618. 17 L. R. A. 4S4;
U. S. v. Lewis (C. C.) Ill Fed. 632;
Nye v. People. 35 Mich. 16. For the distinction between murder and
manslaughter and other forms of homicide, see HOMICIDE; MANSLAUGHTER. Common-law definitions. The willful killing of any subject whatever, with malice
aforethought, whether the person slain shall be an Englishman or a foreigner.
Hawk. P. C. b. 1, c. 13.
Again, there is no tautology in the fact that the acts that constitute the crime of murder are illegal in every country. And there would be no logical conundrum if a country decided to legalize the acts that constitute the crime of murder.