No, it isn't. Not when it's legal.
Murder is always an illegal act. Since Vulcan law explicitly permits the kunat kalifee, and Klingon law allows for Worf killing Duras, then by definition, neither of those things can be murder.
The issue at hand is not what is legal on certain Federation worlds, but what is legal in Starfleet itself. As Picard states. Worf isn't just any Klingon. He's a Starfleet officer with codes of theirs to uphold. I started out by saying that Worf should be booted from Starfleet for it, as it's pretty evident that they don't allow dueling or personal killings of a similar nature as part of their code of conduct. They in fact abhor such things. Picard doesn't even really want to accept it in Code of Honor, but seemingly has his hands tied by being beholden to the Ligonians for a vaccine, enough so at least to humor Lutan by pretending it's legitimately a death match, when he actually intends to use his abilities to prevent such an ending.
They don't condone duel killing in Starfleet, Picard doesn't. Kirk doesn't (even though he stupidly got caught up in one) & even Spock admits he knows he is punishable for it. Therefore it is the same as murder (An illegal killing). Maybe some Federation worlds do allow it, but that is not Starfleet, of which Worf/Spock are sworn officers
If the majority of Federation member worlds have legal dueling to the death, then it would be unlikely that such dueling would be illegal in the Federation legal structure. Dueling to the death might be codified in Starfleet regulation
Why would we think 2 constitutes a majority? If anything it's a fringe element that is precariously tolerated, much like Sudan's child marriage laws being an uncomfortable subject for the U.N. of which its a member
It's not clear exactly what Worf was technically reprimanded for. Leaving the ship without permission perhaps?
It's clear what he was dressed down for. The subject at hand was acceptable killing in the Klingon culture, which Picard shoots down as not being compatible with Starfleet codes of conduct, completing his reprimand with a formal one, which we are led to believe is on the same matter. Worf gets off easy by admitting his wrong doing about THAT subject, & because Picard respects & believes him.
Worf is also a citizen of the Klingon Empire. A crime was committed against his family, and he took care of it in a legal manner on Klingon soil.
Picard has Worf on being AWOL, nothing else.
While in active duty as a representative of Starfleet, on a mission involving the killed party, gaining access to those Klingon grounds only through his position on a Starfleet vessel, during a mission involving it
If Worf petitioned for a leave of absence, or outright resigned his commission like in Redemption, & took his butt to Qu'onos, & killed Duras there, outside of his role as a Starfleet officer, then yes. Starfleet has nothing to say about it. He did not do that. He left his post to kill somebody
Even that I'm not too sure of. It's possible the whole thing went down while Worf was off-shift, and therefore he would never technically be AWOL. Picard could get him on something about leaving the ship without authorization I guess.
You don't stop being an officer bound by a uniformed code of conduct by simply being off duty. You still represent them, especially if you are serving on their ship at the time
