Classical Sunni jurisprudence generally held that offensive jihad required declaration by a legitimate caliph or recognized ruler, making it, in the standard juristic category, fard kifayah, a collective obligation satisfied if enough of the community undertakes it, while defensive jihad against an invading force became fard ayn, an individual obligation binding on every capable Muslim in the threatened territory regardless of any ruler's call. The four classical Sunni schools of law developed their own detailed and not always identical positions on questions including which non-Muslims could be fought, the status and treatment of prisoners, and the distribution of any resulting spoils, while agreeing on a core set of conduct rules drawn from hadith attributed to the Prophet and his companions: prohibitions on killing non-combatants including women, children and monks, on destroying crops and orchards without military necessity, and on mutilating the dead, rules classical jurists treated as binding limits on legitimate warfare rather than as optional counsel.
Twelver Shia classical jurisprudence developed a further distinctive position, holding that offensive jihad required the presence of the infallible Imam and was therefore suspended during his occultation, permitting only defensive jihad in his absence, a doctrinal difference with substantial historical consequences for Shia political theology.