1. Suit on the contract: Where the parties have formed a legally enforceable contract, and the defendant (but not the plaintiff) has breached the contract, the plaintiff will normally sue "on the contract." That is, he will bring a suit for breach of contract, and the court will look to the contract to determine whether there has indeed been a breach, and for help in calculating damages.

2. Quasi-contract: But in other circumstances, the plaintiff will bring a suit in "quasi-contract." Here, the plaintiff is not really asking for enforcement of the contract; instead, he is usually asking for damages based on the actual value of his performance, irrespective of any price set out in the contract. Situations where a quasi-contract recovery may be available include:

1. Specific performance: A decree for specific performance orders the promisor to render the promised performance. (Example: A contracts to sell Blackacre to B on a stated date for a stated price. A then wrongfully refuses to make the conveyance. A court will probably award specific performance. That is, it will order A to make the conveyance.)

2. Injunction: An injunction directs a party to refrain from doing a particular act. It is especially common in cases where the defendant is sued by his former employer and charged with breaching an employment contract by working for a competitor. (Example: D signs a contract with P, his employer, providing that D will not work for any competitor in the same city for one year after termination. D then quits and immediately goes to work for a competitor. If P sues on the non-compete, a court will probably enjoin D from working for the competitor for the year.)

1. Inadequacy of damages: Equitable relief for breach of contract will not be granted unless damages are not adequate to protect the injured party. Two reasons why damages might not be adequate in a contracts case are: (1) because the injury cannot be estimated with sufficient certainty; or (2) because money cannot purchase a substitute for the contracted-for performance. (Example of (2): Each piece of land is deemed "unique", so an award of damages for breach by the vendor in a land sale contract will not be adequate, and specific performance will be decreed).

2. Definiteness: The court will not give equitable relief unless the contract's terms are definite enough to enable the court to frame an adequate order.

3. Difficulty of enforcement: Finally, the court will not grant equitable relief where there are likely to be significant difficulties in enforcing and supervising the order. (Example: Courts usually will not grant specific performance of a personal service contract, because the court thinks it will not be able to supervise defendant's performance to determine whether it satisfies the contract.)

1. Breach by buyer: Courts also often grant specific performance of a land-sale contract where the seller has not yet conveyed, and it is the buyer who breaches. (Example: A contracts to sell Blackacre to B. If A fails to convey, a court will order him to do so in return for the purchase price. If B fails to come up with the purchase price, the court will order him to pay that price and will then give him title.)

1. No specific performance: Courts almost never order specific performance of a contract for personal services. This is true on both sides: the court will not order the employer to resume the employment, nor will it order the employee to perform the services.

2. Injunction: But where the employee under an employment contract breaches, the court may be willing to grant an injunction preventing him from working for a competitor. The employer must show that: (1) the employee's services are unique or extraordinary; and (2) the likely result will not be to leave the employee without other reasonable means of making a living.

1. Expectation: In most breach of contract cases, the plaintiff will seek, and receive, protection for his "expectation interest." Here, the court attempts to put the plaintiff in the position he would have been in had the contract been performed. In other words, the plaintiff is given the "benefit of his bargain," including any profits he would have made from the contract.

2. Reliance: Sometimes the plaintiff receives protection for his reliance interest. Here, the court puts the plaintiff in as good a position as he was in before the contract was made. To do this, the court usually awards the plaintiff his out-of-pocket costs incurred in the performance (including preparation to perform) he has already rendered. When reliance is protected, the plaintiff does not recover any part of the profits he would have made on the contract had it been completed.

3. Restitution: Finally, courts sometimes protect the plaintiff's "restitution interest." That is, the court forces the defendant to pay the plaintiff an amount equal to the benefit which the defendant has received from the plaintiff's performance.