Invalidation of legal acts refers to the negative conclusion drawn by the law after evaluating the established legal acts according to certain standards (conditions). In other words, the legal consequences presupposed by the parties cannot occur because the legal act does not have the conditions for entry into force.

Invalid legal acts generally include: ① acts that violate the mandatory provisions of the law, acts that violate social public interests or social morality, and acts that do not conform to the statutory form in some countries. (2) an act aimed at evading legal constraints, that is, achieving an illegal purpose in a legal form. (3) the hypocrisy of the parties' collusion, that is, there is no expression of intention that makes it legally effective.

(4) The actor is unqualified, including the behavior of a person without capacity, individual behaviors that a person with limited capacity (see natural person) can't implement according to law, behaviors that the actor can't know the consequences of his own behavior in a state of insanity, and behaviors that he has no authorization or obligation to represent others.

Classification of invalid legal acts

① According to its effectiveness, it can be divided into absolute invalidity and relative invalidity. Absolute invalidity means that no matter who is invalid, the invalid legal act is absolute in principle; However, although hypocrisy is invalid between the parties, it cannot be used against a bona fide third party, which is relatively invalid. Some scholars call revocable legal acts relatively invalid, while invalid legal acts are absolutely invalid.

(2) According to the invalid scope, it can be divided into all invalid and one invalid. If all the contents of the legal act are invalid, of course, they are completely invalid; If only a part of an act is invalid and the rest can still be established, according to the principle of "the effective part is not damaged by the invalid part" in Roman law, the rest can still be valid, which is called invalidity.

(3) According to the beginning period of invalidity, it can be divided into initial invalidity and subsequent invalidity. The former refers to the existence of invalid factors when a legal act is established, which makes it impossible for the act to take effect; The latter is valid when the legal act is concluded, but it is invalid due to invalid factors afterwards. For example, in bequest, the legatee dies before the legatee. Subsequent disability is different from inability to pay. For example, in futures trading, before delivery, the subject matter becomes illiquid, which means that payment cannot be made, but it is not invalid afterwards.