This is one of the few dietary rulings on which every school of Sunni and Shia jurisprudence speaks with a single voice, and it functions, in practice, as one of the clearest outward markers of Muslim identity across very different cultures. It sits inside the wider architecture of halal (permitted) and haram (forbidden), and the further category of tayyib, wholesome or pure food, which many scholars read as adding a standard of quality and health on top of bare lawfulness.
Where the schools do disagree is at the margins: whether a derivative product counts as pork once its original substance has been chemically transformed. The Hanafi school generally accepts istihala, transformation, as sufficient to permit something like gelatin once the source material has become, in substance, a different thing, while Shafii and Hanbali jurists have tended to hold that an item of pig origin remains prohibited regardless of processing, a stricter reading that shapes the modern halal certification industry's caution around gelatin, emulsifiers, and enzymes of uncertain origin.
The Islamic ban runs parallel to, but developed independently of, the Jewish judgment that the pig is not kosher. Torah law (Leviticus 11:7) gives an explicit criterion, that the pig has a split hoof but does not chew the cud, and Maimonides later offered a hygienic rationale for the kosher laws generally; normative Islamic scholarship, by contrast, has largely resisted assigning the pig prohibition any single stated reason, preferring to leave it, like much ritual law, a matter of submission rather than explanation.