The recognition of the autonomy of will is a principle specific to private law branches, including of the civil law, and the use of the notion of legal will is essential, because a legal act cannot be conceived without an exteriorised manifestation of the psychological will aimed at causing a legal effect. The effectiveness of the civil legal act must not be categorical, because, although the parties have not created, amended or extinguished a legal relationship in order to cause effects for other parties, however, such effects are produced, namely, third parties that, although not involved in this legal relationship, to a certain extent and with reference to certain matters, cannot ignore the effects it has produced. Therefore, there are, on the one hand, exceptions from the relativity principle and, on the other hand, there is the obligation that third parties have to observe the legal act, to take it into account, and to not ignore it categorically. The enforceability of the legal act on third parties are defined as the parties' right to use the existence of the act, and the effects thereof by reference to the third parties that would put forward claims related to the rights acquired by the parties, and also, the third parties' right to use the existence of the legal act and put it forward for their benefit and against the parties. In order to be able enforce certain legal acts on third parties, the law has established certain formalities as a protection measure for third parties' interests, in the absence of which it is not enforceable on them, and the breach thereof entails the non-enforceability as a sanction in addition to voidance of the civil legal act.
