Think Fight Club
Actually, this still-practiced German ritualized sword combat is somewhat more orderly, though much less legal.
Combatants are members of fighting fraternities, which generally restrict membership to students at the local university. Each fraternity has its own colors, generally worn on an armband to identify members. There is rarely any serious animosity between one fraternity and another.
In a mensur, the two opponents are wrapped in padding of leather, silk, and other cloth to protect their arms, chest, and throat from the razor-sharp schlagers used in the duel. Eyes are covered with specially-made goggles and only the cheeks and forehead are left exposed.
Combatants are placed within a sword-length of eachother and once fighting begins it is not stopped except for bleeding or an act of dishonor. An act of dishonor includes retreating (legs are generally held in place by one's fraternity-mates) or flinching but does not include parrying.
Once blood is drawn, the mensur is halted and the wound is inspected by a doctor (who is present for all mensur). If the wound is less than one onch wide or one inch deep, the fight continues until such a wound is produced.
I don't know if this is still the case, but it was once quite fashionable for schlager fencers to pour sand in a wound so that it would puff up and appear much more prominent, a literal battle scar.
For a fascinating first-hand account of a mensur, read J. Christoph Amberger's The Secret History of the Sword.