Why can’t the dissenting States just secede from the Union?
It is a democracy after all.
It is a democracy after all.
In its simplest form, the civil war wasn't fought because the north thought slavery was bad. It was fought because several states tried to leave the United States.
Hint: Most of the secession declarations include language like this:
> But an increasing hostility on the part of the non-slaveholding States to the institution of slavery, has led to a disregard of their obligations, and the laws of the General Government have ceased to effect the objects of the Constitution.
Citation needed.
If such a thing were to happen, the states that ended up on each side would probably end up doubling down on the oppression of those in the other tribe who are still in their state, to encourage them to move to a state that's on their side.
Individual self determination.
If a local majority secedes every time it wants to trample on a minority, or in the case of the civil war, an oppressed majority, two things happen: one, politics devolve into fractured feudalism. Local elites have a mechanism for wresting absolute control. That, not the Constitution or a Bill of Rights or elections, becomes the basic unit of power.
Two, our two-plus century record of peace on the homeland shatters. Every election or court case found unseemly by a contiguous local majority prompts a Twitter and existential crisis. Foreign adversaries hammer the wedge and split the nation into warring vassal states and too-small-to-matter opposing countries.