<p>Antarias:</p>
<p>While the Civil War from a practical standpoint settled the issue of leaving the Union, legally, the issue is not so clear cut. There was a book published once called “The South was right”, which was quite convincing.</p>
<p>Also, you might note that during the war of 1812, it was the northeastern states that wanted to leave the Union. And I don’t remember reading that people at that time argued that legally they couldn’t do it, but I am not sure about that. </p>
<p>And also, there is the argument that different rules apply to Texas, because it was a sovereign country for a couple years before it became a state.</p>