Committing a crime means doing something unlawful.If it's illegal it's a crime. If one country defines certain acts as being murder and illegal and a different country doesn't define these same acts as being murder and illegal doing these same acts wouldn't be murder in the second country.If a country legalized the acts that previously were illegal and defined as murder a person committing these same acts wouldn't be a murderer or criminal.
This is called a tautology. Murder is per definition a crime. If the act wasn't a crime it wouldn't be murder.The acts must be criminalized otherwise the acts can't be called murder in the first place.If they legalized the acts the acts wouldn't be murder anymore.
So no one is able to show that there is any logical obstacle in any country legalizing the acts that constitute the crime of murder in every country.Perhaps you could unconfuse me as to the meaning of "without any warrant,justification, or excuse in law. " i.e. if you have "warrant, justification or excuse in law" it is not murder i.e. any killing within the law cannot be murder i.e it is necessarily illegal.
And to add a layer of nuance to your example I noted that there is no absolute consensus throughout time and place as to what differentiates murder from acceptable killing other than one is legal and the other is not.
It should also be noted that law and morality are not identical. Many killings that are technically illegal are not considered immoral by many people in many societies. Examples would be mob justice, honour killings, revenge killings, killings of adulterers, killing of blasphemers or other 'social undesirables' like drug addicts, ideological enemies or the wrong ethnic or religious minority.
In addition, it might well be that laws reflect a social pragmatism, more than common morality at times.
There are plenty of historical examples.
The Spartans used to send their kids out to hunt innocent villagers at night to hone their skills. Failure to do so would be shameful and you would be considered a coward and a traitor who put the life of some untermensch ahead of the preservation of your culture. Ergo, killing them was the moral thing to do.
Likewise in many cultures you would be expected to kill (or at least brutally chastise) a slave who disrespected you in public. Failure to do so would be seen as pathetic not of high moral standing.
A human killing another human with 'malice a forethought' has been acceptable for countless reasons (not including warfare).
Can you, in your own words, explain what 'murder' is in a way that makes it morally incorrect/illegal across time and space, rather than having a high degree of cultural and temporal specificity?
In a previous post, I noted one of the acts that would constitute the crime of murder in every country: killing a person merely because one wishes to take his car for a joy ride. Another act that would constitute the crime of murder in every country is killing someone because he owes you money.
If there is no logical conundrum to legalizing the acts that constitute the crime of murder, then the proposition, “Every country criminalizes the acts that constitute murder,” is not a tautology. Logic does not require any country to criminalize any act.