Code of the Duel
I suppose it's the ultimate arms law -- here is a Code Duello drawn up by a convention of gentlemen in Ireland in 1777, and subsequently accepted by custom throughout Great Britain.
It actually has few regulations regarding the duel itself, and much more on what manner of apology must be given in order to avoid it. The first to insult must be the first to apologize, even if the response was more insulting. Actually slapping the other person is so severe an offense that an apology cannot be made save by handing the other person a cane and invited them to cane you (or you must fire three shots, and then you can apologize without offering the cane). For some offenses, honor is restored by two shots without a hit, others require three. If the challenge is made without specifying grounds, one shot suffices, and the most trifling of flesh wounds counts as a hit and ends the duel.
An insult to a lady under a gentleman's care is automatically one higher level than it would be if offered to the gentleman himself. An insult to a fellow in the course of defending a lady's reputation is such that only a slight apology is needed.
The seconds must be equal in social stature to their principals, since if they have a falling out, they will fight each other. A challenge may not be given at night (the assumption seems to be that at night a person may be inebriated and hotheaded).
The rather late date of this code bears out a point Clayton Cramer has made, that formalized dueling was a novelty in the early American republic. He points out that it was quite rare prior to the Revolution. Then Americans wound up with British and French officers hanging around, and picked up the habit.
I liked Abe Lincoln approach to one challenger. He specificed a duel with cavalry sabers (where his upper body strength gave him an advantage) and that each party must remain within a a box made on the ground, the two boxes being at some distance (giving advantage to his longer arms). He reasoned that he ought to be able to disarm the other fellow this way without having to slice him up. I think the other declined.