DoodleDawg: "The Confiscation Acts of 1861 and 1862, upheld by the Supreme Court."
People in rebellion, or at war against the United States, did not receive full protection of the Constitution, especially in matters relating to confiscations & "contraband".
This was true even in the Revolutionary War regarding loyalists.
Also, somewhere I've read, in the First Seminole War, Florida, circa 1818, when James Monroe was President, young John Quincy Adams Secretary of State, and Andrew Jackson in command of US forces invading Spanish Florida.
One of Jackson's actions was to declare slaves of Spaniards freed.
Iirc, Jackson's precedent was recalled by old Adams to young Congressman Lincoln, in 1847.
So it was well understood that people in rebellion could have their property confiscated, including contraband slaves.
And indeed, Confederates themselves practiced contraband confiscations in Unionist regions, to including grabbing any Union blacks they could for return to Confederate slave markets.
I don't recall the "rebellion clause" giving you permission to ignore what the constitution tells *YOU* to do. It's understandable that the people who are breaking away from it might not obey it, but why would the people who are supposedly fighting a war to "save" the constitution, not adhere to it?
I guess Lincoln's thinking went something like this:
"You are breaking the Union created by the Constitution, therefore we shall go to war on you, and to show you we mean business, we will deliberately defy the constitution in pursuit of our war against you "rebels"."
"We have to break the law to save it. "
Yeah, that makes sense.