The unlawfulness of the conduct results either from the breach of a contractual obligation or from a tort, i.e. the violation of commandments or prohibitions of the legal system or of morality.
In the area of tort, this is, for example, the violation of protective laws (e.g. the requirement to drive on the right side of the road), absolutely protected legal interests (e.g. life, health, property) or deliberately immoral conduct.
It should always be noted that the existence of justification for conduct that is in itself unlawful excludes liability. The most important of these justifications are self-defense, necessity and self-help.