In general, an agreement made by a mentally incompetent person is not valid. Above are the six essential elements of a valid contract. This classic approach to contracting has been modified by developments in the Estoppel law, misleading behaviour, misrepresentation, unjustified enrichment and a power of acceptance. A countervailable contract is a contract for which there are infringements that may invalidate the contract. If it is presumed that a contract was not concluded in good faith, it is for the injured party to decide whether it is good, valid and therefore enforceable. A countervailable contract remains valid until it is cancelled as soon as an infringement has been found. If there is a promise to do something, but the agreement does not take into account, the agreement must be concluded in a document. A document is a sealed document that transfers either (i) an interest, right or property, or (ii) creates an obligation that binds someone or certain persons, or (iii) confirms an act that has entrusted an interest, right or property. If a party`s consideration is not entirely clear, the agreement will generally include in the recital languages such as „FOR A GOOD AND VALUABLE CONSIDERATION whose receipt is confirmed“.
An example of a null contract would be that someone is hired by an employer and the terms and conditions of employment require professional responsibilities that are considered illegal. Therefore, the contract would be inconclusive, as it would be contrary to the law, since it contains elements. Acceptance is an agreement under the terms of an offer. Offers can be accepted by behavior. If someone claims to accept an offer but does so on other terms, it is a counter-offer rather than an acceptance.