An unconscionable contract is a contract which is drafted in such a manner that it favors one party and is unfair and harsh on the other party, it gives a higher bargaining power to one party over the other. Such contracts should not be enforceable as they give a greater advantage to one party over the other. 

Such a contract may be drafted by taking an advantage of the mental condition, age, capacity to enter into a contract, the knowledge about the subject, etc. by one party of the other. The courts step in, in case of such contracts and modify the same when at a later date the circumstances make the contract completely one sided making it irrelevant. 

When one party takes an unconscionable advantage of the other, the act may be considered to be a criminal fraud or a civil deceit. 

For example: Where one expert dealer enters into a contract with a customer, who does not have a lot of knowledge about that subject, the contract entered may be an unconscionable one and therefore the court can intervene here and modify the contract.