[rustbucket]

. . . you quoted exactly what I was referring to, the word "necessary" as in, "When in the course of human events it becomes necessary for one people to dissolve the political bands which have connected them with another..."

That is exactly what the seceding states did in 1860-61. NY and RI had defined what was necessary under the Constitution for them to resume their own powers of governance, did they not? The other states accepted those ratifications at the time. Or, perhaps you can show me where those particular ratification statements were not accepted by the other states at the time. All states have the same powers in that regard as any other state.

In fact, as I have pointed out a number of times on FR before, a majority of the 13 original colonies either reserved the right to resume/reassume their own governance or proposed a Tenth Amendment like statement that basically meant the same thing.

As Senator Jefferson Davis pointed out in the Senate in January, 1861:

...the tenth amendment of the Constitution declared that all which had not been delegated was reserved to the States or to the people. Now, I ask where among the delegated grants to the Federal Government do you find any power to coerce a state; where among the provisions of the Constitution do you find any prohibition on the part of a State to withdraw; and if you find neither one nor the other, must not this power be in that great depository, the reserved rights of the States? How was it ever taken out of that source of all power to the Federal Government? It was not delegated to the Federal Government; it was not prohibited to the States; it necessarily remains, then, among the reserved powers of the States.

In 1776 the colonies were breaking away from a government whose king did not allow them to break away. The colonies pointed out why they were breaking away. Some of the states did the same in 1860-61 by listing reasons they thought necessary for them to secede. Some of the states put the question of secession directly to their voters, who were the sovereign voice of the state. That clearly showed that the voters of those states were happier out of the Union, than in it, a-la the "necessary" statements of the NY and RI ratifications. But apparently their 1860-61 secessions did not meet your personal supra-constitutional requirements for secession where you get to define what is necessary.

The reasons for separation were different from those of 1776. Different situation. Apparently you think the states were still colonies trying to break away from the Union under the future King Lincoln. Instead, they were doing what their reserved powers under the Constitution allowed them to do. Or don't you believe in the Tenth Amendment?

So our Founders believed in and practiced disunion from necessity as in 1776.
They also believed in "secession" at pleasure if, and only if, by mutual consent, as in 1788.

The Constitution does not, and never did, prohibit secession, but the Tenth Amendment, which is also part of the Constitution, does allow it. The Tenth Amendment was added to the Constitution because a majority of the thirteen original colonies wanted a safeguard to peacefully get out of what was then a new experimental Union if it became oppressive or no longer in their interest to stay in it. They wanted to retain some of the same rights states individually held before the Constitution.

Why did some Republicans, at least twice - in 1860 and 1861 - propose Amendments to the Constitution that would require acceptance by the central government or other states before a state could secede. They knew that without such amendments that states could secede without permission. The seceding states did not need the permission of the states that might be oppressing them by sectional aggrandizement or by nullifications of the Fugitive Slave Act.

We see once again your interpretation that secession from the Union formed by the Constitution had to have a long list of grievances against the government, other states, etc. Madison, the same guy who proposed the Tenth Amendment, had earlier said "Each State, in ratifying the Constitution, is considered as a sovereign body, independent of all others, and only to be bound by its own voluntary act." Federalist Papers #39.

[Treeless Branch]

If Texas or any other state secedes, and the US does nothing to stop it, it’s legal.

[BroJoeK]

rustbucket: "...apparently their 1860-61 secessions did not meet your personal supra-constitutional requirements for secession where you get to define what is necessary."

Sorry, but it's not about me, or even about you, it is about what our Founders intended for their Constitution.
If you claim to be conservative, then it's about their definitions of "necessity" and "mutual consent", not yours, or even Jefferson Davis'.

As you well know, the best explanation I can find is Madison's letter, here.
Parts of that letter have been quoted on these threads many, many times.
In it Madison makes the case against secession at pleasure:

"Applying a like view of the subject to the case of the U. S. it results, that the compact being among individuals as imbodied into States, no State can at pleasure release itself therefrom, and set up for itself.
The compact can only be dissolved by the consent of the other parties, or by usurpations or abuses of power justly having that effect.
It will hardly be contended that there is anything in the terms or nature of the compact, authorizing a party to dissolve it at pleasure."

Madison also discusses the dire consequences of such disunion, then ends with another analogy:

"Even in the case of a mere League between nations absolutely independent of each other, neither party has a right to dissolve it at pleasure; each having an equal right to expound its obligations, and neither, consequently a greater right to pronounce the compact void than the other has to insist on the mutual execution of it. [See, in Mr. Jefferson's volumes, his letters to J. M. Mr. Monroe & Col. Carrington]"

As to defining the difference between "necessity" and "at pleasure", clearly the 1776 Declaration defines "necessity" where mutual consent is not required, and the 1788 Constitution ratifications define "at pleasure" where mutual consent is required.

So, when did political conditions more resemble those of 1776 "necessity" (requiring no mutual consent) and when of 1788 "at pleasure" -- which did require mutual consent?

1. Clearly, in 1806 when former VP Aaron Burr attempted to secede with Louisiana, that was disunion at pleasure, and President Jefferson had Burr arrested & tried for treason.

2. In 1814 President Madison did not consider New England conspirators at the Hartford Convention arguing for secession due to oppressive Federal policies (the embargo on trade with Britain) -- Madison did not consider such secession "necessary".
   Instead, Madison (who knew something about Founders' Original Intent) responded by moving US Army troops off the border with Canada to Albany in case New Englander threats should result in rebellion.
   Those threats of secession at pleasure ended with Col. Jackson's victory in New Orleans, and resulted in the dissolution of the old Federalist party.

3. By 1820, during President Monroe's Missouri Compromise, Southern threats of secession over slavery were always linked with predictions of civil war:
   "You have kindled a fire which all the waters of the ocean cannot put out, which seas of blood can only extinguish."
   — Representative Thomas W. Cobb of Georgia

   "If a dissolution of the Union must take place, let it be so!
   If civil war, which gentlemen so much threaten, must come, I can only say, let it come!"
   — Representative James Tallmadge Jr. of New York:"

   Nobody in 1820 said there was an unlimited "right to secession" over slavery without civil war.

4. In 1830, when South Carolina threatened secession over President Jackson's "Tariff of Abominations", Jackson ordered US warships and army units to Charleston Harbor, famously saying:
   "...please give my compliments to my friends in your State and say to them, that if a single drop of blood shall be shed there in opposition to the laws of the United States, I will hang the first man I can lay my hand on engaged in such treasonable conduct, upon the first tree I can reach.[65]"

   "John Calhoun, if you secede from my nation, I will secede your head from the rest of your body."

   "On October 19, 1832 Jackson wrote to his Secretary of War:
   "The attempt will be made to surprise the Forts and garrisons by the militia, and must be guarded against with vestal vigilance and any attempt by force repelled with prompt and exemplary punishment."

   President Jackson's 1832 proclamation on Nullification.

Clearly, none of the presidents believed in either an unlimited "right of secession at pleasure", or in the "necessity" of secession at their times.

Nor did either of Presidents Buchanan or Lincoln in 1861.

rustbucket: "Why did some Republicans, at least twice - in 1860 and 1861 - propose Amendments to the Constitution that would require acceptance by the central government or other states before a state could secede.
They knew that without such amendments that states could secede without permission.
The seceding states did not need the permission of the states that might be oppressing them by sectional aggrandizement or by nullifications of the Fugitive Slave Act."

The truth is that before the November 1860 election, there were no negative conditions that any Southern state considered "secession-worthy".
It was only with the constitutional election of Lincoln's "Black Republicans" that some Southerners suddenly cried, "OMG, we just can't stand this any more!"
And yet, literally nothing had changed, in November 1860 Southern Democrats still ruled in Washington, DC, as they had for nearly all of the previous 60 years.

That is the very definition of secession "at pleasure".

As for proposed constitutional amendments and "compromises" intended to preserve the Union: there were many such in 1860 & 1861.
None were considered necessary or viable enough to become law.