Rescission

Undoing a legal act, such as an offer or acceptance of a contract (意思表示, a manifestation of intention), that the law says may be rescinded: for example one made through an important mistake, though a mistake about the circumstances behind the act only if it had been made clear that they were its basis, and as a rule not where the person was grossly careless (Civil Code, Article 95), or one made under fraud or duress, though fraud by a third party only if the other party knew of it or could have known (Article 96), or one a minor made without the consent of their legal representative (Article 5, paragraph (2)). Once rescinded, the act is treated as void from the start (Article 121). Only the person who made it, their representative or successor, or someone whose consent it needed may rescind it (Article 120). The right is lost if not used within five years from when the act could be confirmed — once the mistake, fraud or other cause has ended and the person knows they can rescind (Article 124) — or twenty years from the act (Article 126). It is lost sooner if the person confirms the act, and once it could be confirmed, performing it or demanding performance without reserving objections counts as confirming it (Articles 122 and 125). The Consumer Contract Act adds grounds of its own, such as a business telling the consumer something untrue about an important matter when soliciting the contract, where the consumer believed it and made the contract because of it (Article 4, paragraph (1), item (i)), and gives most of them a shorter time: one year from when the act could be confirmed, and five years from the contract (Article 7, paragraph (1)).