They are described below:
Minor/unsound person /Disqualified person: An agreement made by a minor or an unsound person is void as per the Act. This is because they are not competent parties to a valid contract. As per the Indian Majority Act, a minor is a person who has not attained eighteen years of age. An unsound person is one who is devoid of sound mind either permanently or at the time of making the contract. He is not sound so as to decipher the plus and minus of the contract in which he is involved. This type of void agreement is mentioned in Section eleven of the Act.
Unlawful consideration/object: As per Section 2(d) of the Act, any act or abstinence from doing the act by the promisee with regard to the desire of the promisor is called consideration for the contract. If A promises to deliver 1000 kilogram rice to B if he pays Rs.30000/- to him, then A’s promise to deliver rice forms the consideration for B and B’s promise to pay him money forms consideration of A. Here, for the contract to be valid, the consideration must be lawful. Otherwise, it will be a void agreement.
Section 23 of the Act deals with lawful consideration and objects. If A hires B to kill C and promises a certain amount of money if he does the job, B cannot sue A for not giving the money as the consideration is unlawful. As per the above section, consideration or object are treated unlawful, if it is fraudulent, against public policy, against any law or forbidden by law, or if the Court regards it immoral or involves injury to someone.
Partly unlawful consideration: As per Section 24 of the Act, even if any part of a single consideration for several objects is unlawful and it cannot be separated to make the contract otherwise legal, the whole agreement is void.
Agreement without Consideration: Agreements without consideration is void as stated under Section 25 of the Act. However, there are many exceptions to this rule provided in the above section.
Restraining marriage: If an agreement is made restraining the marriage of any person, such an agreement is void. But such an agreement could be made in case of a minor. Section 26 of the Contract Act deals with this.
Restrains trade or profession: As per Section 27 of the Act, any agreement by which a party restricts the other to do a particular kind of business, trade or profession is void to that extent. A cannot contract with B and say that things purchased from A cannot be sold to a particular class of people in resale or that should not be used for a particular business which is also legal to do. However, in case of the sale of goodwill of a business, the contracting party can incorporate such restraint. He can say the other party not to set up a similar shop within the local vicinity of the other shop owner who sold the goodwill which is likely to attract all the customers of the first party to the buyer’s shop. Here also the restriction must be reasonable. The seller, depending on the nature of goodwill, may not insist that the buyer should not set up a similar business anywhere in the world or at any time. These terms will surely be counted as unreasonable.
A contract of employment usually restricts persons so as to work with the organization for a fixed period. This is valid. However, an employment contract should not contain a clause that after termination the employee should not carry out similar employment which is competitive to the earlier employment and hinder the profit of the earlier organization. Even if contracted such, it is void to that extent.
Restrains legal proceedings: Section 28 of the Act deals with this. A cannot contract with B and say that the latter cannot go to any court, tribunal if there is any fault on the part of the former. Nor he can stipulate a specific time period within which only any claim put forward by B is considered valid. Thus no contract is valid if it discharges any party from contractual liabilities and restricts the other from enforcing his rights after a particular period. Such contracts are void as per the above section. However, an agreement of arbitration to a present/future dispute is valid.
Uncertain agreements: Section 29 of the Act deals with uncertain agreements. There should be certainty in an agreement. For instance, if A, being a dog breeder of many varieties, agrees with B to sell all of his dogs to him, it is a valid contract. But here if A agrees to sell dogs to B at a specific rate, such an agreement is not valid as it is uncertain as to which breed of dog A wants to sell.
Wagering agreements: The nature of wagering agreement is such that neither party knows of the result of the future event. This remains uncertain at the time of the contract. For instance, in a horse race, no one is aware of the result. It is something that happens in the future. However, based on the calculations of their own, the parties enter into an agreement that the winner must be paid by the loser. In the event of non-payment, the winner cannot initiate legal proceedings as it is void agreement as per the Act. The term “wager” is not defined in the Act.
Contingent agreements: Contingent contract is defined under Section 31 of the Act. It is an agreement undertaken by the parties to do or not to do something in case of an event collateral to such contract does or does not happen. Contingent contracts are valid. But if parties made a contingent contract to do or not to do something in case of happening of an impossible event, it is void.
Impossible acts: An agreement to do the impossible act is void. Section fifty-six of the Act deals with it. If A contract with B to make money by magic, this is impossible and hence void. If A contracts with B to marry his daughter C, it is valid and later when C dies the contract becomes void as the act turned impossible. There is a doctrine connected with this particular section known as “doctrine of frustration”. A law note on the same point is published in this link.