A few years from now, perhaps 10 or so, after a horribly botched first-contact led to the temporary conquest of humanity by aliens until humans could adjust to alien technology, humans are once again in charge of their own destinies
Of course, with the massive uphevals that accompanied the destruction of nations and governments and given that humans are now barreling around the lawless galaxy in alien-designed Alcubierre warpships, space piracy is rife, what with the minimal presence of antipiracy warships.
Still, piracy is a business, and those who choose such a life are a rough bunch, and the leadership of one of the more successful groups wants to formalize and codify rules for duelling. Their aim in doing so is to reduce the infighting in their command to a point where it is manageable, yet not turn their crews into wimps and cowards. To that end, their goals are:
Minimise deaths and the severity of injuries while allowing for the ocurrence of injuries and a few deaths - the risk of injury and death must be real, even if reduced in frequency and severity.
Utilize weapons and/or skills that are easily constructed or obtained and easily maintained - where applicable using late 20th to early 21st Century technology
Utilize weapon or skill types that are of use to a pirate in his/her role as a member of a spaceborne boarding party.
It must take significant skill more than mere luck to cause injury or death to an opponent in the context of a duel, in order to encourage practise in the use of the weapons in question.
The risk to bystanders and starships (which are constructed more along in the style of a seagoing cruise ship than an aircraft or a thin-skinned spacecraft subject to the tyrrany of the rocket equation) must be minimized though need not be eliminated.
While this code would originate to keep order and encourage bravery and practising combat skills amongst a pirate crew, it must also be applicable to a planetbound civilian population - pirates do retire sometimes.
Despite having access to alien nanotechnology, Alcubierre drives and reactionless thrusters, many of the the weapons in use are still those of circa 2030 had aliens never appeared - think a lot of RPGs, AK-47s and 9mm semi-automatic pistols, and not many advanced weapons at all. Any duelling weapon must be able to be made by a human without nanotech assistance, and must not use any form of active aiming assistance. A device such as a laser sight, if permitted, would be considered to be a passive aiming assistance. On the other hand, all the weapons mentioned in this paragraph are much too powerful to be allowed, unless modified.
What should a complete duelling code specify, what alternatives should it offer, and what should it not specify. Options for unarmed combat, melee-armed and firearm combat should be considered. Where firearm combat is concerned, what specifications should the weapons and ammunition have? What environments should be specified, if any? What protocols for challenging an opponent and conducting the duel should be specified - and why if any are not immediately obvious.