Contract Law
Part of the common law series
Contract theory
Contract formation
Offer and acceptance  · Mailbox rule
Mirror image rule  · Invitation to treat
Consideration
Defenses against formation
Lack of capacity to contract
Duress  · Undue influence
Illusory promise  · Statute of frauds
Non est factum
Contract interpretation
Parol evidence rule
Contract of adhesion
Integration clause
Excuses for non-performance
Mistake  · Misrepresentation
Frustration of purpose  · Impossibility
Unclean hands  · Unconscionability
Illegality  · Accord and satisfaction
Rights of third parties
Assignment  · Delegation
Novation  · Third party beneficiary
Breach of contract
Anticipatory repudiation  · Cover
Exclusion clause
Fundamental breach
Remedies
Specific performance
Liquidated damages
Penal damages  · Rescission
Subsets: Conflict of law Commercial law
Other areas of the common law
Tort law  · Property law
Wills and trusts
Criminal law  · Evidence

The parol evidence rule enacts a principle of the common law of contracts that presumes that a written contract embodies the complete agreement between the parties involved. The rule therefore generally forbids the introduction of extrinsic evidence (i.e., evidence of communications between the parties which is not contained in the language of the contract itself) which would change the terms of a later written contract. Image File history File links Scale_of_justice. ... A contract is a promise or an agreement that is enforced or recognized by the law. ... This article concerns the common-law legal system, as contrasted with the civil law legal system; for other meanings of the term, within the field of law, see common law (disambiguation). ... Contract theory is the body of legal thought that investigates normative and conceptual problems in contract law. ... Offer and acceptance analysis is a traditional approach in contract law used to determine whether an agreement exists between two parties. ... The mailbox rule or the postal acceptance rule is a term of common law contracts which determines when a contract has been formed where the parties are communicating via the mail. ... In the law of contracts, the mirror image rule states that an offer must be accepted exactly without modifications. ... In contract law, an invitation to treat (invitation to bargain in the US) is an action by one party which may appear to be a contractual offer but which is actually inviting others to make an offer of their own. ... It has been suggested that this article or section be merged with Consideration under English law. ... The capacity of both natural and artificial persons determines whether they may make binding amendments to their rights, duties and obligations, such as getting married or merging, entering into contracts, making gifts, or writing a valid will. ... Duress in the context of contract law is a common law defence, and if you are successful in proving that the contract is vitiated by duress, you can rescind the contract, since it is then voidable. ... Undue influence (as a term in jurisprudence) is an equitable doctrine that involves one person taking advantage of a position of power over another person. ... In contract law, an illusory promise is one that courts will not enforce. ... The statute of frauds refers to a requirement in many common law jurisdictions that certain kinds of contracts, typically contractual obligations, be done in writing. ... This article or section does not cite its references or sources. ... A standard form contract (sometimes referred to as a contract of adhesion or boilerplate contract) is a contract between two parties that does not allow for negotiation, i. ... An integration clause, in the contract law, is a term in the language of the contract that declares it to be the complete and final agreement between the parties. ... In contract law a mistake is incorrect understanding by one or more parties to a contract and may be used as grounds to invalidate the agreement. ... In contract law, a misrepresentation is a false statement of fact made by one party to another party and has the effect of inducing that party into the contract. ... Frustration of purpose is a term used in the law of contracts to describe a defense to an action for non-performance based on the occurance of an unforseen event which makes performance impossible or commercially impracticable. ... Modal logic, or (less commonly) intensional logic is the branch of logic that deals with sentences that are qualified by modalities such as can, could, might, may, must, possibly, and necessarily, and others. ... Unclean hands is an equitable defense in which the defendant argues that the plaintiff is not entitled to obtain an equitable remedy on account of the fact that the plaintiff is acting unethically or has acted in bad faith with respect to the subject of the complaint. ... Unconscionability is a term used in contract law to describe a defense against the enforcement of a contract based on the presence of terms unfair to one party. ... An illegal agreement, under the common law of contract, is one that the courts will not enforce because the purpose of the agreement is to achieve an illegal end. ... Accord and satisfaction is the purchase of the release from a debt obligation. ... An assignment is a term used with similar meanings in the law of contracts and in the law of real estate. ... Delegation is a term used in the law of contracts to describe the act of giving another person the responsibility of carrying out the performance agreed to in a contract. ... Novation is a term used in contract law and business law to describe the act of either replacing an obligation to perform with a new obligation, or replacing a party to an agreement with a new party. ... A third party beneficiary, in the law of contracts, is a person who may have the right to sue on a contract, despite not having originally been a party to the contract. ... Breach of contract is a legal concept in which a binding agreement or bargained-for exchange is not honored by one of the parties to the contract by non-performance or interference with the other partys performance. ... Anticipatory repudiation (or anticipatory breach) is a term in the law of contracts that describes a declaration by one party (the promissing party) to a contract that they do not intend to live up to their obligations under the contract. ... Cover is a term used in the law of contracts to describe a remedy available to a merchant buyer who has received an anticipatory repudiation of a contract for the receipt of goods. ... An exclusion clause is a term in a contract that seeks to restrict the rights of the parties to the contract. ... Fundamental breach, sometimes known as a repudiatory breach, is a breach so fundamental that it permits the aggrieved party to terminate performance of the contract, in addition to entitling that party to sue for damages. ... In the law of remedies, a specific performance is a demand of a party to perform a specific act. ... Liquidated damages is a term use in the law of contracts to describe a contractual term which establishes damages to be paid to one party if the other party should breach the contract. ... Penal damages are best seen as quantitatively excessive liquidated damages and are invalid under the common law. ... In contract law, rescission (to rescind or set aside a contract) refers to the cancellation of the contract between the parties. ... International private law, private international law or conflict of laws is the branch of private law which regulates lawsuits involving foreign laws or jurisdictions. ... Commercial law or business law is the body of law which governs business and commerce and is often considered to be a branch of civil law and deals both with issues of private law and public law. ... In the common law, a tort is a civil wrong for which the law provides a remedy. ... Property law is the area of law that governs the various forms of ownership in real property (land as distinct from personal or movable possessions) and in personal property, within the common law legal system. ... In the common law, a will or testament is a document by which a person (the testator) regulates the rights of others over his property or family after death. ... The law of trusts and estates is generally considered the body of law which governs the management of personal affairs and the disposition of property of an individual in anticipation and the event of such persons incapacity or death, also known as the law of successions in civil law. ... Criminal law (also known as penal law) is the body of common law that punishes criminals for committing offences against the state. ... The law of evidence governs the use of testimony (e. ... This article concerns the common-law legal system, as contrasted with the civil law legal system; for other meanings of the term, within the field of law, see common law (disambiguation). ... A contract is any promise or set of promises made by one party to another for the breach of which the law provides a remedy. ... The law of evidence governs the use of testimony (e. ...

In order for the rule to be effective, the contract in question must be an integrated writing; it must, in the judgment of the court, be the final agreement between the parties (as opposed to a mere draft for example). One way to ensure that the contract will be found an integration is through the inclusion of a merger clause, which recites that the contract is, in fact, the whole agreement between the parties.

An integrated agreement is either a partial or complete integration. If it contains some, but not all, of the terms as to which the parties have agreed then it is a partial integration. This means that the court found the writing to be a final agreement between the parties (and not mere preliminary negotiations), but also went on to find that some of the terms that the parties agreed upon were left out. On the other hand, if the writing were to contain all of the terms as to which the parties agreed, then it would be a complete integration. The importance of this distinction is relevant to what evidence is excluded under the parol evidence rule. For both complete and partial integrations, any evidence contradicting the writing is excluded under the parol evidence rule. However, for a partial integration, terms that do not contradict the writing but merely add to it are not excluded. Partial integration is a term used when a contract contains some, but not all, terms of agreement for a contract. ...

The parol evidence rule only applies to determining the meaning of a term of a contract; it does not apply when determining whether a right constitutes a term of the contract. Also, despite this rule, the court will examine the factual context surrounding the contract and its formation.

There are a number of exceptions to the parol evidence rule. Extrinsic evidence can always be admitted for the following purposes:

• To work out the subject matter of the contract.
• To resolve an ambiguity in the contract.
• To show that an unambiguous term in the contract is in fact a mistaken transcription of a prior valid agreement. Such a claim must be established by clear and convincing evidence, and not merely by the preponderance of the evidence.
• To show fraud, duress, mistake, or illegal purpose on the part of one or both parties.
• To show that consideration has not actually been paid. For example, if the contract states that A has paid B $1,000 in exchange for a painting, B can introduce evidence that A had never actually conveyed the $1,000.
• To identify the parties, especially if the parties have changed names.
• To imply or incorporate a term of the contract.

In order for evidence to fall within this rule, it must involve either (1) a written or oral communication made prior to execution of the written contract; or (2) an oral communication made contemporaneous with execution of the written contract. Evidence of a later communication will not be barred by this rule, as it is admissible to show a later modification of the contract (although it might be inadmissible for some other reason, such as the Statute of Frauds. Similarly, evidence of a collateral agreement - one that would naturally and normally be included in a separate writing - will not be barred. For example, if A contracts with B to paint B's house for $1,000, B can introduce extrinsic evidence to show that A also contracted to paint B's car for $100. The agreement to paint the car would logically be in a separate document from the agreement to paint the house. Look up ambiguity in Wiktionary, the free dictionary. ... Clear and convincing evidence is the intermediate level of burden of persuasion sometimes employed in the civil procedure. ... Preponderance of the evidence is the level of burden of persuasion typically employed in the civil procedure and administrative law. ... Duress (coercion) (as a term of jurisprudence) is a possible defense, via excuse, by which a defendant may argue that they should not be held criminally liable for actions which broke the law. ... Mistake of law and mistake of fact are two types of defense by excuse, via which a defendant may argue that they should not be held criminally liable for breaking the law or liable for damages under a civil law action. ... It has been suggested that this article or section be merged with Consideration under English law. ... The statute of frauds refers to a requirement in many common law jurisdictions that certain kinds of contracts, typically contractual obligations, be done in writing. ...

Addition information on the parol evidence rule may be found in Restatement 2d of Contracts § 213.