I argue in “The Constitution: Myths and Realities” that the Constitution doesn’t forbid secession and therefore allows it. A couple of key points (though not the only ones) are these:
James Madison, known as the Father of the Constitution, characterized it as a contract, though he used an older word, namely, compact:
The [third Virginia] resolution declares, first, that “it views the powers of the federal government as resulting from the compact to which the states are parties;” in other words, that the federal powers are derived from the Constitution; and that the Constitution is a compact to which the states are parties. [Report on the Virginia Resolutions to the Virginia House of Delegates, January 1800]
What else could it be? Romantic rhetoric to the contrary notwithstanding, the Constitution is not the equivalent of the Ten Commandments or the Bible, handed directly from God or inspired by Him. The Constitution represents a practical arrangement through which the States that ratified it agreed to establish a national government with some degree of power over the States, but power that was carefully limited by enumeration.
In fact,
[t]he Constitution supplanted the Articles of Confederation and Perpetual Union, by the will of only nine of the thirteen States. Madison says this in Federalist No. 43 regarding that event:
On what principle the Confederation, which stands in the solemn form of a compact among the States, can be superseded without the unanimous consent of the parties to it? . . .
The . . . question is answered at once by recurring to the absolute necessity of the case; to the great principle of self-preservation; to the transcendent law of nature and of nature’s God, which declares that the safety and happiness of society are the objects at which all political institutions aim, and to which all such institutions must be sacrificed.
Moreover, in a letter to Alexander Rives dated January 1, 1833, Madison says that
[a] rightful secession requires the consent of the others [other States], or an abuse of the compact, absolving the seceding party from the obligations imposed by it.
An abuse of the compact most assuredly legitimates withdrawal from it, on the principle of the preservation of liberty, especially if that abuse has been persistent and shows no signs of abating. The abuse, in this instance, has been and is being committed by the national government.
Was the Constitution intended to operate forever? On the surface, the answer is “no” because it superseded an agreement of “perpetual union” without specifying that it was also an agreement of “perpetual union” — an omission that could hardly have been lost on the delegates to the convention of 1787 or the States’ ratifying conventions. There is also contemporary evidence that the Constitution wasn’t expected to be “perpetual”; for example:
At the end of the Constitutional Convention, George Washington said, "I do not expect the Constitution to last for more than 20 years." (Source here.)
Thomas Jefferson [proposed] that the nation adopt an entirely new charter every two decades. A constitution “naturally expires at the end of 19 years,” he wrote to James Madison in 1789. “If it be enforced longer, it is an act of force, and not of right.” (Source here.)
Moreover, according today’s unanimous opinion in New York v. New Jersey, a State need not prove abuse of the constitutional compact by the national government in order to withdraw from the compact, though proof of abuse (of which there is plenty) would prove valuable in the “court of public opinion”. All that as State must do (Lincoln et al. to the contrary notwithstanding) is to withdraw (secede) from the compact.
Justice Brett Kavanaugh, author of the Court’s unanimous opinion, spells it out:
The question presented is straightforward: Does the Waterfront Commission Compact allow New Jersey to unilaterally withdraw from the Compact notwithstanding New York’s opposition? The answer is yes….
Because the Compact’s text does not address whether a State may unilaterally withdraw, we look to background principles of law that would have informed the parties’ understanding when they entered the Compact. This Court has long explained that interstate compacts “are construed as contracts under the principles of contract law.”… To that end, the Court has looked to “background principles of contract law” to interpret compacts that are silent on a particular issue….
Under the default contract-law rule at the time of the Compact’s 1953 formation, as well as today, a contract (like this Compact) that contemplates “continuing performance for an indefinite time is to be interpreted as stipulating only for performance terminable at the will of either party.”… Parties to a contract that calls for ongoing and indefinite performance generally need not continue performance after the contractual relationship has soured, or when the circumstances that originally motivated the agreement’s formation have changed, for example….
In sum, background principles of contract law, reinforced here by principles of state sovereignty and the fact that the States did not intend for the Compact to operate forever, indicate that New Jersey may unilaterally withdraw from the Waterfront Commission Compact. To be clear, the contract-law rule that we apply today governs compacts (like this Compact) that are silent as to unilateral withdrawal and that exclusively call for ongoing performance on an indefinite basis.
There you have it: a precedent that any State can use to argue that it has the right to withdraw from the compact known as the Constitution, and therefore from the confederation known as the United States of America.
In his book, The Real Lincoln, Thomas DeLorenzo includes an appreciable amount of discussion of the subject of secession. Although I have not fact-checked his research, here are some highly relevant excerpts: "Many of the state voting margins [on ratification of the Constitution]were quite slim (89 to 79 in Virginia; 30 to 27 in New York; 34 to 32 in Rhode Island), and these three states declared in their ordinances of ratification that, being sovereign states, they reserved the right to secede from the Union.” The central thesis of The Real Lincoln is this: "LINCOLN DID NOT LAUNCH a military invasion of the South to free the slaves. No serious student of history could deny this fact. In 1861 Lincoln's position—and the position of the Republican Party—was that Southern slavery was secure: He had no intention of disturbing it; and even if he did, it would be unconstitutional to do so. This is what he said in his First Inaugural Address....The reason Lincoln gave for launching a military invasion of the South was to “save the Union.” Translating from his obfuscating rhetoric, this means that he wanted to use military force to destroy once and for all the doctrines of federalism and states’ rights that had, since the founding of the republic, frustrated ambitious politicians like himself."