Q.Explain discharge of a contract by supervening impossibility, with examples.

Sometimes an outside event, after a contract is signed, makes it genuinely impossible or unlawful to carry out — and the law lets the contract die rather than force the impossible.

Section 56 makes a contract to do an act, which after the contract is made becomes impossible, or, by reason of some event the promisor could not prevent, unlawful, void from the moment the act becomes impossible or unlawful. This is the Doctrine of Frustration.

Examples:

• Destruction of subject-matter — a hall booked for a concert burns down before the event; performance is now impossible.
• Death/incapacity — a singer contracted to perform at a specific event dies or falls seriously ill before the date; a personal-skill obligation cannot be transferred to anyone else.
• Change of law — a new law bans the specific goods a contract required a party to supply, after the contract was made.
• Outbreak of war — trading with a party who becomes an enemy alien on the outbreak of war can no longer lawfully continue.
• Non-occurrence of a contemplated event — a room is hired specifically to view a coronation procession; the procession is cancelled, frustrating the very purpose both parties had in mind.

Once frustrated, the contract becomes void and both parties are discharged from further performance.

Believing that ANY unforeseen difficulty (a price rise, a strike, general commercial hardship) frustrates a contract — frustration requires genuine impossibility or unlawfulness, not mere increased difficulty or expense.