Contract Act, 1872 — Section 33: Enforcement of contracts contingent on an event not happening

33. Enforcement of contracts contingent on an event not happening. Contingent contracts to do or not to do anything if an uncertain future event does not happen can be enforced when the happening of that event becomes impossible, and not before. Illustration A agrees to pay B a sum of money if a certain ship does not return. The ship is sunk. The contract can be enforced when the ship sinks.