«ما استبيح مع قيام السبب»
Something becomes permissible although the ordinary cause of its prohibition still exists.
The book illustrates this with life-threatening coercion to consume carrion or wine, and with makhmasah, an extreme famine or hunger threatening survival.
The ordinary prohibition remains intelligible, but a genuine need to preserve life can allow what would ordinarily be forbidden, to the extent required. Preference, convenience, or appetite is not equivalent to this kind of necessity.