The SCOTUS has ruled that the CSA was never a independent country, just the US in a state of rebellion and the succession was illegal. There are points on both sides of this but the victors write the history so there we have it, the CSA never existed.
So what is the status of the Confederate flag(s) flown at that time. Was it proper to fly the CSA flag for the confederate troops?
Sort of a self-answering, self-cancelling question, I think.
Any rebel force is going to have a flag and uniforms and all the other nationalistic emblems of Who They Are and Why They Fight. (Under the Geneva Convention, they have to. Not identifying your forces is a no-no.)
The rebels are fighting for the legitimacy of that flag and all it stands for. The opponents, especially in a civil or secession war, are going to view it as illegitimate.
So was the CSA uniting and fighting under the Stars and Bars* “legal”? Yes, in their view. No, in the US’s view. US won. While that eliminated the CSA and their flag as a recognized nation or entity, it didn’t change how both sides viewed it during the conflict.
Furthermore, the flag that’s usually thought of as the Confederate flag wasn’t the official flag of the Confederacy at all. It was just the battle flag of the Army of Northern Virginia. There were actually several variants of the official flag just during the time of the Civil War:
Yeah, Og knows we’ve covered this plenty in recent threads. I’ll just point out that all flags under an official national flag are subject to pretty much the same interpretation as I gave above.
Just as the many variations of the national flag, army flags and battle flags were in that little scrum about 80 years earlier. 
Ignorance fought.
No snark… but you didn’t pick this up from the plentiful discussions of the last week or so? I thought it was fairly widely known - had been mentioned enough in the last couple of decades - that the “Confederate Flag” wasn’t the Confederate flag.
Maybe far fewer people understood this than we thought. Answers a number of questions.
Sarcasm fought.
I was trying not to be sarcastic… was I whooshed instead?
The battle flag of the Army of Northern Virginia was square. The most common variant of what is commonly known as the "Confederate flag’ seen today is triangular, and is basically identical to the the battle flag of Army of Tennessee and (for a brief period) the Confederate Naval Jack.
(Bolding mine.) For certain four-cornered values of “triangle.” 
(post shortened)
FYI - This is the CSA flag that is known as the “Stars and Bars” flag -
I’m not familiar with any Supreme Court decision on this issue.
But the CSA was never a legitimate country under international law (because the CSA was never recognized by another country which is one of the requirements to qualify as a country). Therefore, the CSA flag was never “legit” as in the flag of a country.
That recognition was needed and its lack was a concern to the CSA. They sent missions to other countries to get that recognition (and support), but no country would recognize it.
But since the CSA had hopes of being a real country, of course they’d have flags to fly.
Was that true in 1861?
I know that in the postwar, UN era it’s a requirement. But how far back does it go? Was every rearrangement of mitteleuropa subject to “recognition” by other countries for validity?
Even before the UN, you needed some other country to recognize you as a country. You may not have had universal recognition, but someone had to agree that your claims were legit.
For instance, Elizabeth I styled herself as Queen of France. No one in Europe accepted that claim.
But that’s not quite the same thing. I assume that France was still recognized as a country, and its ambassadors, trade, money, treaties etc. all still respected… or at least “recognized.”
So what was the last “country” established by drawing a line around itself, grabbing a sword and saying, “Come get some!” - regardless of how the surrounding or formerly source countries thought of it?
(ETA: Thought about this for two seconds, but I’m NOT gonna go there…)
The most recent candidates might be Eritrea, South Sudan, or Kosovo, depending on the degree of recognition by other countries you would accept.
Okay, back it up, then. What’s the last widely- or fully-accepted such country… and does it take more than recognition by one UN member country for validation?
From a practical perspective it seems to me the only way the Confederate Flag (whichever one) might not be “legit” is if a small subset of the population of the South were the ones that started and kept fighting “for the South” AND were fighting other southerners who were trying to STOP them.
While there was obviously differences in opinion on the matter, I don’t think the civil war rose to that level.
Something more like the IRA claiming to represent Ireland might be be an example of that though.
Seems to me, any legitimacy it may have claimed, was undone by the many public politicians who openly called it ‘the white man’s banner’, back when they were insisting on flying it in front of the state capital.
Just to clarify:
[ul]
[li]The first Confederate flag, called The Stars and Bars,was this one.[/li]
The number of stars in the circle on the blue canton changed as a new state joined the Confederacy (same as the stars on the American or Union flag). Starting with 7 stars, it eventually would contain 13. This flag was found to be flawed in that it resembled the Union flag too much and it caused confusion on the battlefield (flags weren’t just symbolic back then, they showed commanders the position of the moving battle lines).
[li]The second Confederate flag, called The Stainless Banner,was this one.[/li]
Note that this is **NOT **merely the controversial ‘rebel flag’, it is a white flag with the so-called ‘rebel’ symbol as the canton (the white flag blends with the white background in the Wiki page). Here is an actual flag. This flag was also flawed in that when it hung unfurled on a flagpole it too closely resembled a white flag of surrender.
[li]The third (and final) Confederate flag, called The Blood Stained Banner, was this one.[/li]
Because of the second flag resembling a white flag of surrender a vertical red stripe was merely added to the existing flag’s outside edge. This flag saw little use as the Confederacy surrendered soon after its adoption.
[/ul]
As has been stated above, *none *of these three official flags of the Confederacy were the controversial rebel flag.
IMO since the Confederacy lost the war the Confederate flag was never an official flag of any territory. During the course of the war it was still all US territory under various phases of rebellion. There’s a great line in Ken Burn’s The Civil War when historian Shelby Foote recounts a Union General telling Lincoln how they had driven the rebels out of Union territory, to which Lincoln frustratingly replies, “When will you people understand, it’s all our territory!”
