A mere consent is not enough for a valid contract. One of the essentials of a valid contract mentioned in Section 10 is that the parties should enter into the contract with their free consent. Section 13 defines consent as, Two or more persons are said to consent when they agree upon the same thing in the same sense that is consensus ad idem. In other words, there must be real consent, in the absence of which there is no contract formed. When there is no consent, the agreement is void.

However, in certain cases there is real consent, but one of the parties has given his consent not out of his free will but due to factors in the absence of which he might not have given his consent. Consent so given is said to be not free. In such cases, the contract is voidable.

According to Section 14, consent is said to be free when it is not caused by-

1. coercion (Section 15), or
2. undue influence (Section 16), or
3. fraud (Section 17), or
4. misrepresentation (Section 18), or
5. mistake, subject to the provisions of Section 20, 21 and 22.

Consent is said to be so caused when it would not have been given but for the existence of such coercion, undue influence, fraud, misrepresentation or mistake. Where consent to an agreement is caused by coercion, undue influence, fraud or misrepresentation, the agreement is a contract voidable at the option of the party whose consent was so caused. If, for example, a person is induced to sign an agreement by fraud, he may, on discovering the truth, either uphold the contract or reject it. Where consent is caused by mistake, the agreement is void, A void agreement is not enforceable at the option of either party.

Examples of No free consent

1. A threatens to shoot B, if B does not agree to sell his property to A at a stated price. B’s consent has been obtained by ‘coercion.’
2. A, a man enfeebled by disease or age, is induced, by B’s influence over him as his medical attendant, to agree to pay B an unreasonable sum for his professional services, B employs ‘ undue influence.’
3. A husband persuaded his illiterate wife to sign certain documents telling her that by them he was going to mortgage her two lands to secure his indebtedness and in fact mortgaged four lands belonging to her. This was an act done with the intention of deceiving her that is a case ‘ of fraud.’
4. The Government auctioned certain forest coupes. A part of the land was occupied by tenants. The Forest Department knew this fact but did not disclose to the purchaser. The contract is vitiated by ‘ misrepresentation.’
5. 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 on account of ‘ mistake.’