Just that--the Federation in total, acting through the Federation Council. It has been a custom of some to separate out Section 31 as a rogue operation and to place the responsibility for use of the virus on them and them alone, at least in quantity of writing. Rogue or not, sanctioned or not, their infecting of the Great Link was sanctioned after the fact by the Federation through the Federation Council when in the Dogs of War the Council refused to give the Founders the cure.
In my opinion Odo does not speak for the writers here because he is a changeling. His feelings are hardly unbiased here, and Sisko comes off as a man who wants his disapproval to be an acceptable stand-in for really sticking to principles. He also comes off as a total hypocrite to me in targeting scapegoats and in this pretension that he has some moral high ground to speak from after the events of In the Pale Moonlight. He makes Sec 31 a scapegoat right after he has acknowledged that it is now the Federation's ball. He gets to cluck about how he doesn't like it and still reap its benefits while grumblingly explaining that, "oh, yeah, they started this shit." Because the aggressor DOES lose a significant moral position in any physical conflict:
SISKO: The Federation Council considered giving the Founders the cure, then they decided against it.
ODO: Then they're abetting genocide.
SISKO: I don't condone what Section Thirty One did, but the Founders started this war, not us. Giving them the cure would strengthen their hand. We can't do that. Not when there are still millions of men and women out there putting their lives on the line every day. (DS9, The Dogs of War)
But whether you approve of the use of the virus or not, any simple scapegoating of Section 31 is simply ethically empty. The Federation had the cure and refused to give it. Odo states the reality here, a statement that calls Sisko on his singling out of Sec 31:
ODO: Interesting, isn't it? The Federation claims to abhor Section Thirty One's tactics, but when they need the dirty work done, they look the other way. It's a tidy little arrangement, wouldn't you say?
He's right and he's wrong in my view. Right in the mechanics of it, and in its explicit meaning that this tactic of war belongs to the legitimate Federation authorities now, they own it, can't disown it, and so it is a LEGAL-in-every-sense-of-the-word act, but wrong that it was either abhorrent or dirty. It was certainly a step not lightly taken, but millions of dead Federation citizens make the choice not abhorrent, but simply hard and unpleasant.
No matter how you slice it though, and no matter if you think the tactic was wrong or right, Sec 31 is not the ultimate owner of this tactic, the Federation is.
