Vitiating factors constituting defences to purported contract formation include:
Mistake (such as non est factum)[93]
Incapacity, including mental incompetence and infancy/minority
Misrepresentation or fraud
Such defenses operate to determine whether a purported contract is either (1) void or (2) voidable. Void contracts cannot be ratified by either party. Voidable contracts can be ratified.
Main article: Misrepresentation
Misrepresentation means a false statement of fact made by one party to another party and has the effect of inducing that party into the contract. For example, under certain circumstances, false statements or promises made by a seller of goods regarding the quality or nature of the product that the seller has may constitute misrepresentation. A finding of misrepresentation allows for a remedy of rescission and sometimes damages depending on the type of misrepresentation.
In a court of law, to prove misrepresentation and/or fraud, there must be evidence that shows a claim was made, said claim was false, the party making the claim knew the claim was false, and that party's intention was for a transaction to occur based upon the false claim.[94]
There are two types of misrepresentation: fraud in the factum and fraud in inducement. Fraud in the factum focuses on whether the party alleging misrepresentation knew they were creating a contract. If the party did not know that they were entering into a contract, there is no meeting of the minds, and the contract is void. Fraud in inducement focuses on misrepresentation attempting to get the party to enter into the contract. Misrepresentation of a material fact (if the party knew the truth, that party would not have entered into the contract) makes a contract voidable.
Assume two people, Party A and Party B, enter into a contract. Then, it is later determined that Party A did not fully understand the facts and information described within the contract. If Party B used this lack of understanding against Party A to enter into the contract, Party A has the right to void the contract.[95]
The foundational principle of “caveat emptor,” which means “let the buyer beware,” applies to all American transactions.[96] In Laidlaw v. Organ, the Supreme Court decided that the buyer did not have to inform the seller of information the buyer knew could affect the price of the product.[97]
According to Gordon v Selico [1986] it is possible to misrepresent either by words or conduct. Generally, statements of opinion or intention are not statements of fact in the context of misrepresentation.[77] If one party claims specialist knowledge on the topic discussed, then it is more likely for the courts to hold a statement of opinion by that party as a statement of fact.[98]
It is a fallacy that an opinion cannot be a statement of fact. If a statement is the honest expression of an opinion honestly entertained, it cannot be said that it involves any fraudulent misrepresentations of fact.[99]
For an innocent misrepresentation, the judge takes into account the likelihood a party would rely on the false claim and how significant the false claim was.[100]
Remedies for misrepresentation. Rescission is the principal remedy and damages are also available if a tort is established. In order to obtain relief, there must be a positive misrepresentation of law and also, the person to whom the representation was made must have been misled by and relied on this misrepresentation:Public Trustee v Taylor.[101]
Contract law does not delineate any clear boundary as to what is considered an acceptable false claim or what is unacceptable. Therefore, the question is what types of false claims (or deceptions) will be significant enough to void a contract based on said deception. Advertisements utilizing "puffing," or the practice of exaggerating certain things, fall under this question of possible false claims.[102]
Main article: Mistake (contract law)
A mistake is an incorrect understanding by one or more parties to a contract and may be used as grounds to invalidate the agreement. Common law has identified three types of mistake in contract: common mistake, mutual mistake, and unilateral mistake.
Common mistake occurs when both parties hold the same mistaken belief of the facts. This is demonstrated in the case of Bell v. Lever Brothers Ltd.,[103] which established that common mistake can only void a contract if the mistake of the subject-matter was sufficiently fundamental to render its identity different from what was contracted, making the performance of the contract impossible.[104] In Great Peace Shipping Ltd v Tsavliris Salvage (International) Ltd, the court held that the common law will grant relief against common mistake, if the test in Bell v. Lever Bros Ltd is made out.[105] If one party has knowledge and the other does not, and the party with the knowledge promises or guarantees the existence of the subject matter, that party will be in breach if the subject matter does not exist.[106]
Mutual mistake occurs when both parties of a contract are mistaken as to the terms. Each believes they are contracting to something different. Courts usually try to uphold such mistakes if a reasonable interpretation of the terms can be found. However, a contract based on a mutual mistake in judgment does not cause the contract to be voidable by the party that is adversely affected. See Raffles v Wichelhaus.[107]
Unilateral mistake occurs when only one party to a contract is mistaken as to the terms or subject-matter. The courts will uphold such a contract unless it was determined that the non-mistaken party was aware of the mistake and tried to take advantage of the mistake.[108][109] It is also possible for a contract to be void if there was a mistake in the identity of the contracting party. An example is in Lewis v Avery[110] where Lord Denning MR held that the contract can only be voided if the plaintiff can show that, at the time of agreement, the plaintiff believed the other party's identity was of vital importance. A mere mistaken belief as to the credibility of the other party is not sufficient.
Main articles: Duress (contract law) and Undue influence
Duress has been defined as a "threat of harm made to compel a person to do something against his or her will or judgment; esp., a wrongful threat made by one person to compel a manifestation of seeming assent by another person to a transaction without real volition."[111] An example is in Barton v Armstrong [1976] in a person was threatened with death if they did not sign the contract. An innocent party wishing to set aside a contract for duress to the person only needs to prove that the threat was made and that it was a reason for entry into the contract; the burden of proof then shifts to the other party to prove that the threat had no effect in causing the party to enter into the contract. There can also be duress to goods and sometimes, 'economic duress'.
Undue influence is an equitable doctrine that involves one person taking advantage of a position of power over another person through a special relationship such as between parent and child or solicitor and client. As an equitable doctrine, the court has discretion. When no special relationship exists, the question is whether there was a relationship of such trust and confidence that it should give rise to such a presumption.[112][113][114]
Main article: Unconscionability
In Australian law, a contract can be set aside due to unconscionable dealing.[115][116] Firstly, the claimant must show that they were under a special disability, the test for this being that they were unable to act in their best interest. Secondly, the claimant must show that the defendant took advantage of this special disability.[117][115]
Main article: Illegal agreement
If based on an illegal purpose or contrary to public policy, a contract is void. In the 1996 Canadian case of Royal Bank of Canada v. Newell[118] a woman forged her husband's signature, and her husband agreed to assume "all liability and responsibility" for the forged checks. However, the agreement was unenforceable as it was intended to "stifle a criminal prosecution", and the bank was forced to return the payments made by the husband.
In the U.S., one unusual type of unenforceable contract is a personal employment contract to work as a spy or secret agent. This is because the very secrecy of the contract is a condition of the contract (in order to maintain plausible deniability). If the spy subsequently sues the government on the contract over issues like salary or benefits, then the spy has breached the contract by revealing its existence. It is thus unenforceable on that ground, as well as the public policy of maintaining national security (since a disgruntled agent might try to reveal all the government's secrets during his/her lawsuit).[119] Other types of unenforceable employment contracts include contracts agreeing to work for less than minimum wage and forfeiting the right to workman's compensation in cases where workman's compensation is due.
Setting aside the contract
To rescind is to set aside or unmake a contract. There are four different ways in which contracts can be set aside. A contract may be deemed 'void', 'voidable' or 'unenforceable', or declared 'ineffective'. Voidness implies that a contract never came into existence. Voidability implies that one or both parties may declare a contract ineffective at their wish. Kill fees are paid by magazine publishers to authors when their articles are submitted on time but are subsequently not used for publication. When this occurs, the magazine cannot claim copyright for the "killed" assignment. Unenforceability implies that neither party may have recourse to a court for a remedy.
Ineffectiveness arises when a contract is terminated by order of a court, where a public body has failed to satisfy the requirements of public procurement law. This remedy was created by the Public Contracts (Amendments) Regulations 2009, (SI 2009/2992).