19. When consent to an agreement is caused by coercion, fraud or misrepresentation, the agreement is a contract viodable at the option of the party whose consent was so caused.  
A party to a contract, whose consent was caused by fraud or misrepresentation, may, if he thinks fit, insist that the contract shall be performed, and that he shall be put in the position in which he would have been if the representations made had been true.  
Exception.–If such consent was caused by misrepresenta-tion or by silence, fraudulent within the meaning of section 17, the contract, nevertheless, is not voidable, if the party whose consent was so caused had the means of discovering the truth with ordinary diligence.  
Explanation – A fraud or misrepresentation which did not cause the consent to a contract of the party on whom such fraud was practised, or to whom such misrepresentation was made, does not render a contract voidable.  
Illustrations  (a) A, intending to deceive B, falsely represents that five hundred maunds of indigo are made annually at A's factory, and thereby induces B to buy the factory. The contract is voidable at the option of B.  
(b) A, by a misrepresentation, leads B erroneously to believe that five hundred maunds of indigo are made annually at A's factory. B examines the accounts of the factory, which show that only four hundred maunds of indigo have 
been made. After this B buys the factory. The contract is not voidable on account of A's misrepresentation.  
(c) A fraudulently informs B that A's estate is free from encumbrance. B thereupon buys the estate. The estate is subject to a mortgage. B may either avoid the contract, or may insist on its being carried out and the mortgagedebt redeemed.  
(d) B, having discovered a vein of ore on the estate of A, adopts means to conceal, and does conceal, the existence of the ore from A. Through A's ignorance B is enabled to buy the estate at an under-value. The contract is voidable at the option of A.  
(e) A is entitled to succeed to an estate at the death of B; B dies: C, having received intelligence of B's death, prevents the intelligence reaching A, and thus induces A to sell him his interest in the estate. The sale is voidable at the option of A.  
Power to set aside contract induced by undue influence  
19A. When consent to an agreement is caused by undue influence, the agreement is a contract voidable at the option of the party whose consent was so caused.  
Any such contract may be set aside either absolutely or, if the party who was entitled to avoid it has received any benefit thereunder, upon such terms and conditions as to the Court may seem just.  
(a) A's son has forged B's name to a promissory note. B, under threat of prosecuting A's son, obtains a bond from A for the amount of the forged note. If B sues on this bond, the Court may set the bond aside.  
(b) A, a money-lender, advances Taka 100 to B, an agriculturist, and, by undue influence, induces B to execute a bond for Taka 200 with interest at 6 per cent per month. The Court may set the bond aside, ordering B to repay the Taka 100 with such interest as may seem just.]  
Agreement void where both parties are under mistake as to matter of fact  
20. Where both the parties to an agreement are under a mistake as to a matter of fact essential to the agreement, the agreement is void.  
Explanation - An erroneous opinion as to the value of the thing which forms the subject-matter of the agreement is not to be deemed a mistake as to a matter of fact.  
(a) A agrees to sell to B a specific cargo of goods supposed to be on its way from England to Chittagong]. It turns out that, before the day of the bargain, the ship conveying the cargo had been cast away and the goods lost. Neither party was aware of the facts. The agreement is void.  
(b) A agrees to buy from B a certain horse. It turns out that the horse was dead at the time of the bargain, though neither party was aware of the fact. The agreement is void.  
(c) A, being entitled to an estate for the life of B, agrees to sell it to C. B was dead at the time of the agreement, but both parties were ignorant of the fact. The agreement is void.  
Effect of mistakes as to law  
21. A contract is not voidable because it was caused by a mistake as to any law in force in Bangladesh; but a mistake as to a law not in force in Bangladesh has the same effect as a mistake of fact.  
Illustrations  
A and B make a contract grounded on the erroneous belief that a particular debt is barred by the Bangladesh Law of Limitation: the contract is not voidable.  
Contract caused by mistake of one party as to matter of fact  
22. A contract is not voidable merely because it was caused by one of the parties to it being under a mistake as to a matter of fact.  
What considerations and objects are lawful and what not  
23. The consideration or object of an agreement is lawful, unless- it is forbidden by law; or  
is of such a nature that, if permitted, it would defeat the provisions of any law; or  
is fraudulent; or  
involves or implies injury to the person or property of another; or the Court regards it as immoral, or opposed to public policy.  
In each of these cases, the consideration or object of an agreement is said to be unlawful. Every agreement of which the object or consideration is unlawful is void.  
Illustrations  
(a) A agrees to sell his house to B for 10,000 Taka. Here B's promise to pay the sum of 10,000 Taka 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 Taka. These are lawful considerations.  
(b) A promises to pay B 1,000 Taka 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's promises to pay A 1,000 Taka 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 Taka 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 has 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 Taka 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 Penal Code.