As a legal concept, duress has a long tradition. Duress is related to the concept of undue influence. Duress exists when there is a threat of bodily harm, and the threat is immediate and cannot be avoided. Duress also exists in criminal law proceedings. In order for duress to exists in a contract law court proceeding there must be a wrongful or illegal threatened act. 

A contract also cannot normally be made voidable because one of the parties is suffering from economic duress. Claims of duress are filed by parties to a contract seeking to prove that their assent to a contract was not genuine, and thus did not fulfill the essential requirements needed to form a contract.

A contract cannot be invalidated by a party to that contract who claims duress because the other party threatened to sue them for a larger amount, because the filing of a law suit is a legally permitted action. A claim of duress is distinct from instances where the consideration offered by one of the parties is the forbearance of an action. 

Duress can be invoked if the party claiming they were acting under duress was in fear for their safety. An example of duress would be if a person is told to sign a contract or their family or they themselves would be harmed. This qualifies as duress because the consideration of forbearance is to forbear from doing an illegal act. If it is a wrongful or illegal threatened act then it constitutes an instance of duress.

A claim of economic duress is not usually permitted. Individuals are usually only able to successfully invoke a claim of economic duress if the other party in the contract is the immediate cause of the economic duress. Sometimes the courts permit a claim of economic duress to be filed in contracts which involve one party claims they are suffering from economic difficulties which are not caused by the other party in the contract, although such claims of economic duress are not usually accepted. 

Economic duress does not exist simply if exorbitant prices are charged for goods or a service. However, if the high prices are charged by the same party that created the need for the good or service then a claim of economic duress may be permitted by the courts.

If the individual claiming the contract was formed under duress is able to prove their claim, then the courts may declare the contract voidable. 

Non-fraudulent misrepresentation can take one of two forms: innocent misrepresentation or negligent misrepresentation. Negligent misrepresentation is considered in the eyes of the law to contain the same level of culpability as fraudulent misrepresentation.

Misrepresentation that is negligent in nature is treated by the courts in the same way as a fraudulent misrepresentation. Negligent misrepresentation occurs when a party to a contract does not carry out a reasonable effort to ensure that their claims as the material information at the heart of the contract are true.

If one of the parties to the contract in question does not act with the professionalism that would reasonably be expected from an individual in that position, and the other party relies on that professionalism when entering into the contract, then negligent misrepresentation may be determined by the courts to have happened.

An unconscionable contract is unenforceable. It is immaterial whether a waiver is explicit or implicit. Procedural unconscionability also gives rise to an unconscionable contract if one of the parties is in a vastly superior bargaining position.

An unconscionable contract may also contain substantive unconscionability if the terms of the contract are excessively harsh or would be oppressive to implement. An unconscionable contract can also result if the party selling the goods marks up the price tremendously and attempts to hide how great the mark up is.

Whether a contract is conscionable or unconscionable can only be determined by a judge and never by a jury.

During the contract drafting process every attention must be paid to ensuring that an illegal contract is not created. As a result, individuals responsible for contract drafting employ several safeguards to attempt to decrease the probability that they create an illegal contract.

Some of these preventative methods include using boilerplate language, which are terms used in a majority of contract drafting negotiations, as well as employing lawyers or people with a legal background in the contract drafting. However, even when these safeguards are employed, illegal contracts can still result.

Even if illegality is found to exist in a contract, it may still be enforceable in pari delicto, then a legal contract will not be ruled to exist.

If the violation of the law in question is not of a serious nature, then the illegal contract may be enforced as if it were a legal contract. If the compensation that would have to be provided in the event the contract was declared illegal would be out of proportion to the infraction of the concerned law, then the contract may be enforced as if it were a legal contract. The agreement may also be treated as a legal contract if the court determines that there would be an unjust enrichment to one of the parties in the event that the contract drafting was set aside.

If a contract is ruled to be illegal after actions have been done by one of the parties which cost money, the idea of quantum meruit may come into play. Under quantum meruit, which means “as much as deserved,” an individual may be able to recoup expenses in proportion to their outlay of money for services performed in an illegal contract if they performed the actions under the belief they were executing a legal contract.

Unlike in a legal contract, quantum meruit does not entitle the individual invoking it to hold the other person liable for the terms of the contract. This legal concept only allows the individual to recoup their losses.

A severable contract is a contractunenforceable that can still remain in effect despite those provisions which are void. In order for the blue pencil test to be satisfied, the phrase stricken by the court must not result in a change to the purpose for which the contract was created by the parties. The contract must still make grammatical sense after the edits have been made to the contract. Otherwise the contract will not be considered to have become a severable contract.

A severable contract can be formed if the parties who entered into the contract do not consider it essential that all the actions be performed together. Divisible contracts may exist if a convenience store orders the soda, chips and candy it sells from the same company in three separate clauses. An indivisible contract is formed if the store hired a vendor to provide the soda, chips, and candy in a single clause. 

Whether divisible contracts or indivisible contracts have been formed can often be determined by examining the terms under which consideration has been provided. If the set of contracts provide the consideration in a lump sum, it is usually an indivisible contract. If consideration is itemized for each thing exchanged, a severable contract often exists.

If a contract contains both legal and illegal clauses, the court will attempt to enforce only the legal clauses in the event the contract is already a severable contract. If the court can employ a blue pencil test to create a severable contract, it will.

Fraudulent misrepresentation by silence may result during a long contract negotiation if one of the parties to the contract withholds material information they learned during the negotiation process.

A contract can be challenged by one of the parties to the contract if they claim their assent was not genuine because they were subject to undue influence. Undue influence is said to exist if an inordinate amount of pressure is placed upon a party to enter into a contract against their best interests. Undue influence cannot be invoked by a party simply because they are in a detrimental contract. 

Undue influence is usually only claimed in the event that the party is in a relationship wherein another person is able to influence their decisions. Normally undue influence can only be successfully claimed by a minor or an elderly person who has a guardian responsible for overseeing their legal or financial obligations.

Other relationships in which undue influence may arise include attorney-client relationships, doctor-patient relationships, and the relationships between the beneficiaries of a trust and the individual responsible for managing the trust.

An occurrence of undue influence can be difficult to establish conclusively in court. There is sometimes an automatic presumption of undue influence by the courts. A presumption of undue influence can be established if the party in the superior position influenced the dependent party to agree to a contract that benefited the superior party.

If the dependent party challenges a party that they were influenced to create by their guardian, the courts are likely to issue a presumption of undue influence because they believe that if the contract did not arise due to undue influence, then the dependent would not be challenging the contract.

The guardian involved in a court case in which the genuineness of assent in a contractual dispute involves a presumption of undue influence often bears the responsibility of disproving the charge filed against them by their ward. The undue influence charge is often repudiated by presenting evidence that the ward inquired about the terms of the contract or was afforded the opportunity to consult with an independent party that did not have a direct stake in the contractual negotiations that are being challenged.

The guardian can disprove that there has been an occurrence of undue influence even if there was a benefit conveyed to the guardian if they can demonstrate that the ward received a full disclosure of the benefit that the guardian would derive from the contract. If the guardian can prove that full disclosure was presented to the ward, that the ward obtained independent analysis of the benefits that all involved parties would receive, then the presumption of undue influence can be disproven.

In the event that undue influence is found to have existed by the courts, the courts will declare the contract to be voidable by the ward. Undue influence, however, cannot be claimed by a ward that acted upon the innocent advice of their guardian yet was harmed by the contract in a way that did not benefit the guardian.