Summary. The article is devoted to the investigation of optional legal rules of civil law. It discloses the notion of optionality in the civil law, determines its formal and essential features. It analyses the importance of optionality as the key feature of the optional norm of law. It discloses the kinds (types) of the optional rules of civil law and defines the mechanisms guaranteeing the effectiveness of such rules. Non-mandatory based on the rule of law and constantly interacts with them as the form and
content, that is why it is the basis of differentiation norms of law on the mandatory and nonmandatory, and therefore should investigate the legal discretionary rules and their delimitation from mandatory. Dispositive legal norm is not characterized by the representative absolute-binding character, but only mustn’t contradict the general principles of civil law (Part 1. .. Article 6 of the Civil Code of Ukraine). Non-mandatory norms are opposed to mandatory, which have clear, strict formulation, consolidation in the law acts and do not allow the posibbility of implementing judicial powers to the participants in the application of civil law norms. Formation of non-mandatory norms are not made arbitrarily, but based on the will of the parties and the implementation of their autonomous will which eventually are fixed by certain regulatory formulas (legislative and individual undernorms in the settlement of of relations nonamed signing contracts). It takes place by fixing of normative formula, the phrase «... if another is not envisaged (it is set) by an agreement / by a law or agreement of parties (by an agreement)», or legislative fixing of exceptions: «after the exceptions set by a law», «... if other (longer) term (size, order etc.) does not envisaged according to the agreement of parties (by an agreement)», or general permission of alternative rule of behavior, that is it arising from the context set of fixed rules of general action. In the latter case, in the event of a dispute the court deciding a particular case will push off from general principles of civil legislation and search for a norm that parties followed at the settlement of relations between them, as a rule, by means of analogy of law or analogy of right. Exactly civil prescriptions has signs of normativeness (the obligatoryness of fixing is in the act of civil legislation), differ in representatively-obligatory character, and their totality makes a non-mandatory civil legal norm the rule of behavior is formed that.
Keywords: optionality, self-regulation, optional rule of civil law, civil law regulation, normative legal prescription, acts of civil legislation