How was the Emancipation Proclamation constitutional?

[politicallefty]

This is a question that's been bothering me for awhile, I have to admit. Obviously, the Emancipation Proclamation was a profound statement and one that set the stage for constitutional abolition only a few years later. What I don't understand is how it was constitutional or under what authority the President himself had to issue such a proclamation. The Constitution at its adoption was without question pro-slavery. I don't see how that can be disputed. It considers the issue a number of times in different ways. Am I missing something?

[politicallefty]

I don't want to make it seem like I'm arguing in opposition of emancipation obviously, but it seems like that's a vast overreach of presidential power and also a violation of the Takings Clause of the 5th Amendment. I'm also fairly sure the Fugitive Slave Act was still in force at that time, though obviously the Confiscation Acts could have obviated some of those provisions. The United States never recognized the Confederate States as legitimate, so the Constitution in its entirety should theoretically have applied to the so-called Confederacy during the Civil War.

[politicallefty]

I'm not trying to debate here, so I'm not going to quote everything. I'm just trying to figure this out logically for my own sake.

Okay, so it's probably settled that President Lincoln's power to do so came at least in part from Congress passing the Confiscation Acts because it doesn't seem like the powers as Command-in-Chief and over rebellion and insurrection are enough to justify the action constitutionally. The Confederacy may have been in open rebellion against the United States, but according to US law and Supreme Court precedence, unilateral secession was not constitutional and therefore the Constitution never stopped applying. How was the Takings Clause not violated?