You absolutely can, in a boxing ring for example. It's not unconstrained violence if it takes place within a framework of rules - i.e. it's a sport. NFL tackles being the same thing.

A Twitter feed showing _only_ illegal violent NFL tackles? Well, that might just get banned now.

You said "unconstrained", but that's not what this is about. I agree that Twitter has just entered a completely unwinnable situation, and they made a mistake because nothing they do will be balanced by everyone's definition. I'm saying the "it's not violence if it's consensual" point is ridiculous and wrong. Additionally, and perhaps obviously, I was talking about a duel, not a sport [0].

[0] https://en.wikipedia.org/wiki/Duel

Well we're sort of violently agreeing, albeit obliquely. I owe you a response; you got unfairly downvoted for what was obvious sarcasm and I think my initial response cast your comment in a bad light.

> "it's not violence if it's consensual" point is ridiculous and wrong.

Exactly - provided that it's done outside the boundaries of some sport. But I think an actual lawyer would need to say what that means: could you and I, for example, create a new sport called "Modern Dueling" and construct a set of rules for it which permits us to fight to the death in a seemingly regulated fashion? Almost certainly not: no reasonable person would consent to be bound by those rules. Yet people do die in MMA, for example, and charges are not bought. It's part of the accepted risk of the sport which is regulated and refereed to prevent lasting harm to participants.

Would two knuckleheads who decided to dress up in NFL gear and run full tilt at each other in a parking lot face charges? What if one of them died? I'd guess yes. Again, I agree with you.