Historically, short of revolution or rebellion, secession is the ultimate practical check on centralization.
No branch of the federal government is empowered to decide upon the merits of a State's inherent right to secede. By its very nature, secession is an anti-federal act not requiring federal sanction.
Petitioning the federal government for permission to secede is self-contradictory and has no basis in English common law or American constitutional history. Secession/rescission/withdrawal is a unilateral action and is not dependent upon mutual agreement between the parties to that contract.
When one enters into a contract and the other party violates that contract, does one request permission of the offending party to withdraw from that contract already violated? Of course not. All compacts are subject to the equitable remedy of rescission in the event of a breach of contract. It's really common sense, basic contract law. It's that straightforward.
At its inception, the US of A was a voluntary compact (contract) of sovereign States, each retaining the inherent authority to rescind its contractual relationship with the federal government, the other party to that contract, should the latter violate the terms of that contract/compact. That contractual relationship hasn't changed, though the misnamed "civil war" may have led us to believe otherwise. (By the way, "civil war" means that two or more factions are militarily struggling over control of the central government; however, in America's so-called "civil war", the South was defending its sovereign territory, not entertaining the capture and control of the central government in DC.)
Force of arms alone by a revisionist, self-contradictory, union-at-any-price nationalist, that being our heretofore venerated Abe Lincoln, cannot--and did not--invalidate a State's inherent right to secede, or to otherwise rescind its ratificaton of this contract, no more than the federal government can legally or constitutionally annul the People's right to rebel in the face of tyranny.
Note: if secession were treasonous, which some maintained it was, why then were not southern leaders dragged into court following the North's successful invasion of the Confederate States of America? Easy. Because the North didn't want to lose in court what they thought they had won on the battlefield.
Perpetual union at any price was never contemplated or embraced by the Founders. Rebellion, secession, nullification, civil disobedience remain essential elements of America's republican fabric, and the threat or application of force on the part of the federal government cannot eradicate those foundational, inherent and unalienable rights of a free people.
When ratifying the Constitution, and only to the extent that it delegated certain of its sovereign powers to the federal government, not once did any State surrender its sovereignty. All powers voluntarily granted by the States to the federal government were very limited and very specific. All other powers not delegated remained with the States. The 10th Amendment enshrined that principle in the Constitution and, in so doing, reasserted the foundational principle that the federal government cannot unilaterally redefine the limits of its powers. To join the union, the States were not compelled to surrender anything, much less their sovereignty.
And remember, we not only seceded from England, but also, one by one, from the Articles of Confederation (which was said to be "perpetual") in order to form the current union of States, a union which was initially comprised of but 9 States, the remaining 3 sovereign States freely opting to remain outside the union until well after the Constitution's adoption. This "MORE perfect union"--MORE perfect, NOT perfect--was not intended or expected to exist in perpetuity, but, like the Articles of Confederation, only until such time that the compact outlived its usefulness. Our Founders, studious historians, were not stupid men and well understood the corruptibility of men and all that man may devise. While our Founders hoped the union would be strong, free and productive, they did not view secession and dissolution as ill-conceived, treasonous or unanticipated. We've just been brainwashed into believing that secession and dissolution are vile, wrong, corrupt and treasonous. Not so at all. If that were true, then our Founders were charlatans and short-sighted fools. They weren't.
All that said, as a first step I recommend that States opt for nullification, the "rightful remedy" as Jefferson described it, to resist unconstitutional acts by the Supreme Court, the Congress, the Chief Executive and their myriad bureaucracies which now comprise the unofficial fourth branch of government. And to render nullification more efficacious, States should enact punitive laws to prohibit the enforcement of those federal acts nullified by the State. This is called "interposition", or a State's insinuating itself between intrusive federal authority and the citizens of the State. Interposition would actually require the arrest, trial and imprisonment of any State OR federal agent who attempts to enforce a nullified federal act. Of course, implicit in nullification is the threat of secession should the invasive federal government fail to retreat to contractual parameters. But, again, secession is not by its nature treasonous or unavoidably violent. Not at all.
Finally, while I sincerely appreciate the wave of secessionist sentiment sweeping the country, secession, a serious constitutional matter, requires a majority of a State's residents to support the act. Anything less than a majority constitutes a protest and nothing more. And even with a majority expressing its support for secession, the people's State representatives must be won over as well, this if the label of "insurrection" is to be avoided and Art I Sec 8 Para 15 be invoked. Note: per Art IV Sec 4 of the Constitution, "on application of the Legislature, or of the Executive (when the Legislature cannot be convened)", the feds can be asked to intervene, whether that intervention is morally repugnant or not. Secession is a political act, not merely a feel-good act. Thus, on the subject of secession, both the people of a State and their duly elected State representatives must be one.
So, to the near one million well-intentioned petitioners around the country, this: without a majority within a State as well as State legislative support, secession is an impossibility. Great PR--maybe--but nothing more.
"The source of Lincoln's power was his willingness to exercise power not grounded in the orginal Constitution but in in his creative abilities to undermine the Constitution while rhetorically defending it." Donald Livingston, "Rethinking the American Union..."
"The secession of a state from the Union depends on the will of the people of such state. The people alone, as we have already seen, hold the power to alter their constitution." William Rawles (1825)