In declaring the Emancipation Proclamation, did Abraham Lincoln or his administration put forth any legal arguments to support or justify it? If so, what were those arguments?

by mowshowitz

In a comment on this post, /u/preservedfish writes:

"British emancipation of rebel-owned slaves was later used as partial evidence that the emancipation of of an enemy's slave was a customary practice in war thus giving Lincoln the power to issue the Emancipation Proclamation as a war measure."

This points to judicial precedence, which in turn implies that the Emancipation Proclamation was formulated with some legal justification in mind. It makes sense that this would be the case, but I've never heard of any legal framework or precedent used to bolster the EP before.

Were such arguments indeed put forth? If so, what were they? If not, why not--did wartime somehow preclude such justification, or was the moral argument deemed sufficient?

petite-acorn

I answered a similar question a few months ago that might get to the heart of what you're look for with this question. See here: https://www.reddit.com/r/AskHistorians/comments/5u2sx1/how_much_of_a_master_stroke_was_lincolns/ddqygoj/

Feel free to shoot me any follow up questions you might have!

TD;LR - The EP was as born out of a military necessity as well as a moral one. By freeing the slaves in the north, it incentivized those looking to run away (out of the Confederacy) and gave the Union's military leaders the legal justification they needed not to return slaves to their masters when on a campaign.