Where does secession contravene the Constitution? In Federalist Paper 39, James Madison, the father of the Constitution, cleared up what "the people" meant, saying the proposed Constitution would be subject to ratification by the people, "not as individuals composing one entire nation, but as composing the distinct and independent States to which they respectively belong." In Federalist Paper 45, Madison guaranteed: "The powers delegated by the proposed Constitution to the federal government are few and defined. Those which are to remain in the State governments are numerous and indefinite."
The State's power to secede is spelled out in the Declaration of Independence. The Constitution does not forbid the State's the power to secede. In fact, the Constitution was specifically amended via the Bill of Rights to ensure "The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people." (9th amendment) "The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people." (10th amendment)
Now tell me where the Constitution forbids the people the right expressed in the Declaration of Independence to form political bonds of their choosing.
Secession per se may not. Unilateral secession as practiced by the southern states does.
The State's power to secede is spelled out in the Declaration of Independence.
The Declarattion of Independence does not found the basis for our laws, the Constitution does.
The Constitution does not forbid the State's the power to secede. In fact, the Constitution was specifically amended via the Bill of Rights to ensure "The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people." (9th amendment) "The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people." (10th amendment)
The Constitution also requires Congressional approval for the admission of a state or any subsequent change in it's status. Implict in this is Congressional approval to leave the Union altogether.
Now tell me where the Constitution forbids the people the right expressed in the Declaration of Independence to form political bonds of their choosing.
Where to begin? Can the people of the states for a government of their own choosing? No, Congress will tell them what kind of government they may have. Can they form political bonds with other states? No. Can they form alliances with foreign nations? No. The Constitution places a lot of restrictions on the political bonds that they can form.