People keep talking about "Federalizing the National Guard" and now you've got other States pledging their NG to Texas in defiance of the Supreme Court (see image).
Abraham Lincoln thought they could not. In his inaugural address, he opined that the union was formed for perpetuity and that if the accession of a state to the union required the consent of all other states, so would its secession. He was, among other things, a lawyer so he usually knew what he was talking about.
Legal Eagle just released a video on exactly this topic. Spoiler: the whole Texas being allowed to secede is basically a myth and pretty much all scholars agree that Texas nor any other state has the ability to leave except by a mutually agreed dissolution or via revolution.
The thing about law though, is that it's just a framework of written social contracts between rational parties agreeing to abide by the terms and consequences.
Reality is a bit different.
Texas could halt physical transport of goods/services. Refuse to buy US imports. Stop collecting tax revenue. Gun down federal employees that don't swear Texan allegiance.
It doesn't really matter what legal papers say, when it comes to actions.
Sure - there may be consequences for such "illegal" state actions, and the documented illegality would be articulated as official justification after administering such consequences.
But that also only matters if Texas is defeated ... in the unlikely event they "win," - they'd write their own narrative with legal justification.
I'm not saying they have any chance - just making the point that "legal" and "illegal" are arbitrary and determined by whoever is the dominant power. Texas seceding is "illegal" only so long as the US remains powerful. If by some unholy miracle, Texas were to win independence from the US, they would probably write their own laws to say rejoining the US is illegal.
Another pair of cases to make my point - the Holocaust was "legal" to the Nazis. After they were defeated, the UN made genocide "illegal." But how many genocides have occurred around the world since 1949?
Laws are only as good as they are enforceable, which is exactly what you underscore by citing the strength of the US military. Is it "legal" to make drone strikes or drop a nuke on Texas? đ¤ˇ
Even if they voted for it and ratified it they couldnât over turn it or legally secede from the USA.
In the 1869 case Texas v. White, the court held that individual states could not unilaterally secede from the Union and that the acts of the insurgent Texas Legislature â even if ratified by a majority of Texans â were âabsolutely null.â
When Texas entered the Union, âshe entered into an indissoluble relation,â Chief Justice Salmon P. Chase wrote for the court. âAll the obligations of perpetual union, and all the guaranties of republican government in the Union, attached at once to the State. The act which consummated her admission into the Union was something more than a compact; it was the incorporation of a new member into the political body. And it was final. The union between Texas and the other States was as complete, as perpetual, and as indissoluble as the union between the original States. There was no place for reconsideration, or revocation, except through revolution, or through consent of the States.â
Chase added: âThe ordinance of secession, adopted by the convention and ratified by a majority of the citizens of Texas, and all the acts of her legislature intended to give effect to that ordinance, were absolutely null. They were utterly without operation in law.â
Another source of confusion and misinformation over the years has been language in the 1845 annexation resolution that Texas could, in the future, choose to divide itself into âNew States of convenient size not exceeding four in number, in addition to said State of Texas.â But the language of the resolution says merely Texas could be split into five new states. It says nothing of splitting apart from the United States. Only Congress has the power to admit new states to the Union, which last occurred in 1959 with the admission of Alaska and Hawaii.
So far as I understand, there is a common idea that Texas has the legal ability to leave it it wants, but it's just a popular myth as far as I'm aware. Whatever their state constitution says doesn't matter anyway, because federal law trumps state laws and as far as I'm know there's not a legal mechanism for states to leave again, it'd have to either get the government as a whole to make legal or possibly even constitutional changes to allow it, or leave illegally, either by force or by having a sympathetic government just not press the matter and just ignore the laws in question. I can't really see them getting enough support for the former two, they're too weak compared to the federal government for an actual war, and the current administration is not likely to just let them go, so I don't expect them to go anywhere unless one of those things drastically changes.