Step 1: Understanding the Concept:
The scenario describes a situation where a contract, which was legal and possible to perform when it was made, subsequently becomes impossible or unlawful to perform due to a change in the law. This is known as the doctrine of "Supervening Impossibility" or "Frustration of Contract."
Step 2: Key Formula or Approach:
The relevant provision is Section 56 of the Indian Contract Act, 1872. The second paragraph of this section states: "A contract to do an act which, after the contract is made, becomes impossible, or, by reason of some event which the promisor could not prevent, unlawful, becomes void when the act becomes impossible or unlawful."
Step 3: Detailed Explanation:
In the given case, the contract to supply oil-seeds was valid when formed. However, the subsequent government order under the Defence of India Rules made the sale and purchase of oil-seeds illegal. This supervening illegality makes the performance of the contract unlawful. According to Section 56, the effect is that the contract becomes void. When a contract becomes void, both parties are discharged from their respective obligations to perform. There is no question of one party being at default or seeking specific performance of a contract that is now illegal.
Step 4: Final Answer:
The effect is that Both parties are discharged from the performance of such contract.