Here again, I address the question at the largest civilizational scale: where does morality come from? What justifies it? (That brings an immediate problem, as regimes, let alone governments, are constantly shifting; consider in China alone the “Warring States”, followed by Qin, followed by Han, then Tang, Sung, Yuan, Ming, etc; these are called dynasties, but they were actually different regimes, constantly shifting; however, pretty much the same morality; so I introduce meta-governance, meta-civilization, etc.)
A criminal regime has criminal laws. They, of course, can be more or less criminal.
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Wayne Straight Indeed but it got me to thinking about whether there is or can be any such thing as a “moral” government. One of my long-time original (at least I think it’s original) quips is that any large organization is only as ethical or moral as it’s least moral member. That would seem to be particularly apt when applied to governments.

Serious Abomination was always legal, making it even more abominable… [Actually the Holocaust of Jews was not even legal according to the Nazis own laws passed in 1935. The Wannsee Conference attempted to persuade the Justice minister and others to allow the bending of Nazi laws… to exterminate Jews, and others…
Answer to Wayne: One has to define first what “moral” is. For doing this, it helps to go back to the etymological root: moral is from Old French moral (14c.) and directly from Latin moralis “proper behavior of a person in society,” literally “pertaining to manners,” coined by Cicero (“De Fato,” II.i) to translate Greek ethikos (see ethics) from Latin mos (genitive moris) “one’s disposition,” in plural, “mores, customs, manners, morals,” a word of uncertain origin.
Conclusion? Morality is defined in a society as what enables sustainability, of said society.
For example neither Assyria, not Imperial fascist Rome, nor the Mayas, nor the Aztecs, nor the Nazi or Stalinian regime were moral, because they were not sustainable. But of course they were more or less sustainable, thus moral: Rome and the Maya lasted millennia, Assyria, centuries, whereas Stalin’s regime lasted 30 years, the Nazis, 12.
Another related notion is meta-governance. Morality arises from meta-governance, not simple governance, because morality is a civilizational notion (after the Nazis were killed by the Allies, Germans immediately recovered the moral sense coming from Western civilization; same thing happened in Russia after the demise of Sovietism).
The West has had metagovernance even as the Occidental Roman state crumbled and partly collapsed: Goths, Burgonds, Franks and remaining Romans agreed, in their various states/kingdoms, upon the basic civilizational structure, namely, mostly that of the Roman state.
Within a century, the Franko-Gallo-Romans had installed a Roman like metagovernance (everybody became a Frank while Frankish and Celtic languages faded, replaced by bastardized Latin).
In the details, the IMPERIUM FRANCORUM looked extremely gory: Frankish leaders, having done away with Goths and Burgonds, and the like, were busy killing each other, in most unpleasant manners. However, on the largest scale, the Imperium Francorum was an important moral advance. The Imperium Francorum became so highly moral, it superseded morally the Greco-Roman meta-civilization preceding it.
Indeed the government of the ruling monarch, the Frankish queen, Saint Bathilde, outlawed the slave trade (of Frankish citizens) around 655 CE (1,210 years before the good old USA outlawed in turn slavery…)
In contrast, metagovernance of Mexico, pre-conquista, was terrible, highly immoral: Aztecs insisted to eat their enemies, so Cortez found plenty of allies, multiplying his army by a factor of 40 or so. That gigantic army overwhelmed the Aztecs (who had boasted countless times that Cortez will never have enough men to kill them all). The immorality of the Aztec regime was the direct cause of its demise: it gave the Spaniards the excuse and capability to exterminate it.
A similar mechanism occurred with Nazism, and other fascisms, of course: their very immorality caused them a mass of enemies bigger than themselves, and provided those enemies with plenty enough motivation, namely the enemies will to survival, for the extermination of the fascists. Nazi laws were so immoral, so unsustainable, the Nazis themselves couldn’t obey them (they had to bend them, hence the infamous Wannsee conference).
So then what to extract from the preceding drastic moral fundamentalism, looking forward?
Well, any new ways and means increasing humanity’s potential survival will define a new and better morality, looking forward.
Patrice Ayme
P/S: What happened to the ethological (somehow genetically, or congenitally imprinted) morality (which advanced animals can be experimentally determined to have)? Well, it’s subjacent and implied in the preceding discourse: the exact same force, the WILL & IMPLEMENTATION of SURVIVAL, which established morality at the civilizational level, established morality ethologically and etiologically at the scale of the evolution of species.