(a) A agrees to sell his house to B for 10,000 rupees. Here B's promise to pay the sum of 10,000 rupees is the consideration for A's promise to sell the house, and A's promise to sell the house is the consideration for B's promise to pay the 10,000 rupees. These are lawful considerations.
(b) A promises to pay B 1,000 rupees at the end of six months, if C, who owes that sum to B, fails to pay it. B promises to grant time to C accordingly. Here the promise of each party is the consideration for the promise of the other party and they are lawful considerations.
(c) A promises, for a certain sum paid to him by B, to make good to B the value of his ship if it is wrecked on a certain voyage. Here A's promise is the consideration for B's payment and B's payment is the consideration for A's promise, and these are lawful considerations.
(d) A promises to maintain B's child, and B promises to pay A 1,000 rupees yearly for the purpose. Here the promise of each party is the consideration for the promise of the other party. They are lawful considerations.
(e) A, B and C enter into an agreement for the division among them of gains acquired, or to be acquired, by them by fraud. The agreement is void, as its object is unlawful.
(f) A promises to obtain for B an employment in the public service, and B promises to pay 1,000 rupees to A. The agreement is void, as the consideration for it is unlawful.
(g) A, being agent for a landed proprietor, agrees for money, without the knowledge of his principal, to obtain for B a lease of land belonging to his principal. The agreement between A and B is void, as it implies a fraud by concealment, by A, on his principal.
(h) A promises B to drop a prosecution which he has instituted against B for robbery, and B promises to restore the value of the things taken. The agreement is void, as its object is unlawful.
(i) A's estate is sold for arrears of revenue under the provisions of an Act of the Legislature, by which the defaulter is prohibited from purchasing the estate. B, upon an understanding with A, becomes the purchaser, and agrees to convey the estate to A upon receiving from him the price which B had paid. The agreement is void, as it renders the transaction, in effect, a purchase by the defaulter, and would so defeat the object of the law.
(j) A, who is B's mukhtar, promises to exercise his influence, as such, with B in favour of C, and C promises to pay 1,000 rupees to A. The agreement is void, because it is immoral.
(k) A agrees to let her daughter to hire to B for concubinage. The agreement is void, because it is immoral, though the letting may not be punishable under the Indian Penal Code (45 of 1860).
Legal Commentary & Landmark Judgments: Section 23
Section 23 of the Indian Contract Act, 1872 establishes the doctrine of legality of object and consideration, striking down agreements that are illegal, fraudulent, injurious, or contrary to public policy.
This statutory framework establishes clear operational guidelines, balancing legal compliance with procedural safeguards.
Section 23 invalidates agreements to stifle criminal prosecutions, champertous litigation arrangements designed to exploit the justice system, and contracts circumventing foreign exchange regulations or tax laws. Where a contract is void for illegality under Section 23, the court leaves the parties where it finds them ('in pari delicto potior est conditio defendentis'), and Section 65 restitution is generally unavailable.