In the real world most countries at least give lip service to the Geneva Conventions
when they go to war. Many works of fiction feature societies with similar rules when it comes to warfare, in fact they're often much more restrictive, to the point of becoming an Obstructive Code of Conduct
. In science-fiction settings these rules often include a moratorium on orbital bombardment
and/or a Nuclear Weapons Taboo
. Sometimes the combatants are factions within one Empire and the rules allow them a limited form of warfare.
Beware the enemy who does not know or blatantly disregards the rules.
- The Great Houses in Dune have Kanly, a set of laws enforced by the emperor's Sardaukar. The big ones include having a legitimate grievance against the opposing house, and no use of atomics on humans.
- Honor Harrington has the Eridani Edict, which requires attacking fleets to take out all orbital ships and structures and offer an opportunity to surrender before bombarding a planet.
- Traveller has the Imperial Rules of War, which are an unwritten guideline as to how Imperial vassals will settle difficulties between them. Basically they boil down to, "Have fun boys, but don't make to much of a mess because The Emperor has means to punish you." "Too much of a mess" meaning no WMDs on the ground, war crimes, or excessive death and destruction.
- The Inner Sphere successor states in BattleTech signed the Ares Conventions to limit civilian casualties. Rules include no nukes in atmosphere, no orbital bombardment of non-military targets, and no chemical or biological weapons. The Clans follow a more restrictive code of conduct called batchall based on highly ritualized warfare, which bit them in the back when they invaded the Inner Sphere.