Apad Dharma (āpad-dharma)

Apad dharma is the dharma of emergencies, the conduct permitted when normal rules would mean destruction: a brahmin may take up arms, a king may deceive, a starving man may eat what is forbidden. Bhishma devotes a whole section of his teaching to it, and the Mahabharata uses it to explain, or at least to frame, the deceptions by which the war is won. The obvious danger is that everyone in a crisis believes their case is exceptional, which is exactly the argument Krishna and Yudhishthira have after Drona's death.