Indian Contact Act 1872: Quasi Contracts

A contract is a result of an agreement enforceable by law. But in some cases there is no offer, no acceptance, and in fact no intention on the part of the parties to enter into a contract and still the law, from the conduct and relationship of the parties, implies a promise imposing obligation on the one party and conferring a right in favour of the other.
In other words, under certain circumstances, obligations resembling those created by a contract are imposed by law through the parties have never entered into a contract. Such obligation imposed by law are referred to as Quasi Contracts or Constructive Contracts.
The Indian Contract Act 1872 deals with quasi-contractual obligations under Sections 68 to 72. Let's take a look at them below:

1.  Necessaries supplied to a Person Incapable of Contracting (Section 68): If a person is incapable of entering into a contract (suppose, A lunatic or a minor etc.) is supplied by another person with necessaries suited to the condition in his life, then he can get reimbursement from the property of the incapable person.                                                   X supplies Z, a lunatic, with necessaries suitable to his condition in his life. X  is entitled to be reimbursed from Z's property. 
2.  Payment made by an Interested Person (Section 69): A person who is interested in the payment of money which another is bound to pay, and who therefore pays it, is entitled to be reimbursed by the other.                                                                                     Z is a zamindar. He has leased his land to X, a farmer. However, Z fails to pay the revenue due to the government. After sending notices and not receiving the payment, the government releases an advertisement for sale of the land (which is leased to X). According to the Revenue law, once the land is sold, X’s lease agreement is annulled. X does not want to let go of the land since he has worked hard on the land and it has started yielding good produce. In order to prevent the sale, X pays the government the amount due from Z. In this scenario, Z is obligated to repay the said amount to John.
   
   
   
   
   
   
3.  Obligation made by a Person enjoying a benefit of Non- Gratuitous Act (Section 70): When a person lawfully doing something or delivering something to someone without the intention of doing so gratuitously and the other person enjoying the benefits of the act done or goods delivered. In such a case, the latter is liable to pay compensation to the former for the act, or goods received.                                                 A, a tradesman, leaves goods at B's house by mistake. B treats the goods as his own. He is bound to pay A for them.
4.  Responsibility of Finder of Goods (Section 71): If a person finds goods that belong to someone else and takes them into his custody, then he has to adhere to the following responsibilities:
   
   • Take care of the goods as a person of regular prudence.
   • No right to appropriate the goods.
   • Restore the goods to the owner (if found).
5.  Money paid by Mistake or Under Coercion (Section 72): A person to whom money has been paid, or anything delivered, by mistake or under coercion, must repay or return it.                                                                                                                                          A and B jointly ower ₹100 to C. A alone pays the amount to C, and B, not knowing this fact, pays ₹100 over again to C. C is bound to repay the amount to B.