It unlawful is what results contrary to straight. It is called straight, in this framework, at set of laws and principles that allow the regulation of social relations based on an ideal of order and justice.
An act is unlawful when It is prohibited by the legal system. The action in question, therefore, is contrary to the law and is constituted as a crime.
That is why it can be said that a crime is an unlawful action. When a person, by reckless or voluntary action or omission, violates the law, adopts unlawful behavior and, if it is typified in the penal code, commits a crime.
It is interesting to mention that, as an act contrary to the rules imposed by the legal system, the crime stands as a unlawful fact. But, in turn, it is a legal fact since it generates effects just legal.
Another way of understanding unlawfulness is as a disvalue. When a law is enacted, the interests or assets to be cared for are defined and an assessment is made that is detailed in the rule. Actions that threaten the interest or the good, in this way, imply a disvalue (a negative value).
It must be taken into account that a conduct, to be considered a crime, must conform to a figure described in the law. However, there are typical behaviors that are not unlawful because they are taken as lawful. That is the case of the call legitimate defense: a person, under certain circumstances, can kill another without that act being classified as a homicide.