linguistic:paraphrasing, stylistic:tone, stylistic:style_transfer
Defences

Defences to claims under contract law include vitiating factors, which defences operate to determine whether a purported contract is either (1) void or (2) voidable, or assertions that the other party failed to perform their obligations within a reasonable period of time. With regard to contracts of a commercial nature, the UNIDROIT Principles of International Commercial Contracts provides a general outline of the grounds under which a contract can be set aside. Where a contract or term is voidable, the party entitled to avoid may either conditionally or unconditionally choose to affirm the contract or term as outlined in Article 3.2.9 of the Principles which states that "if the party entitled to avoid the contract expressly or impliedly confirms the contract after the period of time for giving notice of avoidance has begun to run, avoidance of the contract is excluded". Additionally, Article 3.2.13 provides that "where a ground of avoidance affects only individual terms of the contract, the effect of avoidance is limited to those terms unless, having regard to the circumstances, it is unreasonable to uphold the remaining contract".

Although provisions for the voidability of a contract for conduct of the other party are generally similar across jurisdictions, voidability on the grounds of a third party's conduct is more contentious. Article 3.2.8 of the Principles provides that where conduct constituting grounds for rescission "is imputable to, or is known or ought to be known by, a third person for whose acts the other party is responsible, the contract may be avoided under the same conditions as if the behaviour or knowledge had been that of the party itself". Similarly, while vitiating factors are similar across jurisdictions, the extent to which a failure by another party to a contract may form grounds for rescission or an early termination of contractual obligations varies between jurisdictions. For instance, Mainland Chinese law provides that a party may seek to rescind a contract or terminate its remaining obligations if the other party "expresses or indicates by act that it will not perform the principal obligation", "delays performance of the principal obligation and still fails to perform it within a reasonable period of time", or "delays performance of the obligation or has otherwise acted in breach of the contract, thus making it impossible to achieve the purpose of the contract".