Especially in the comments over at Above the Law, many of whom are obviously lawyers. Massad Ayoob has some worthwhile things to say about defense against unarmed opponents. I don’t think it’s a situation you ever want to be in, and is one reason I’ve been convinced of the utility of carrying a defensive spray.
Multiple attackers is a tough situation, however. And it wouldn’t do much good to spray one guy only to get rushed by others. The advantage of spray is you can employ it much much earlier in the confrontation than you can deadly force. It is a step above verbal commands on the force scale. A good strategy would be, early on in the encounter, before it escalates, to spray the most aggressive member of the group and run like hell, while drawing your firearm. If you’re pursued by the remaining meatheads and end up trapped, your use of deadly force is going to look a lot more reasonable to police, prosecutors, and if it goes that far, to a jury.
Ung’s situation is far from good, however. DiDinato’s group was five strong. Ung had two other people with him, including one female. We don’t know yet whether Ung or any of the people in his group were intoxicated. Even if Ung wasn’t, it could complicate his retreat options if the others are. It could complicate his options if any of the members of his party were running their mouths off.
But generally speaking, if you shoot someone who’s unarmed, you can probably expect a trial, unless it was so clear cut (like a group of men surrounding a sixty year old man) that no prosecutor would risk it. Whether or not Ung acted reasonably, or not, will be up to the jury to decide. Once you’re in that situation, in a lot of ways your life is already ruined.