About Private Crimes in Spain
Private crimes are those that will only be prosecuted through a criminal formal complaint (called in Spain "Querella") by the affected person. This must be signed by a lawyer and a procurator.
In these cases, there is no attack against a general legal right, but rather it is committed on a person. Therefore, neither an unaffected private third party can promote the procedure, nor can the authorities act ex officio in the face of a private crime.
The Spanish Penal Code recognizes as private crimes:
Slander ("Calumnias"): Imputing a third party the commission of a crime, with the knowledge of its falsehood. That is to say, someone is accused of having committed a criminal act (constituted as such in the Criminal Code) knowing that it is not true that it was committed or with reckless disregard for the truth.
Insults ("Injurias"): impute to another, manifestations of opinions or facts that affect his dignity, undermine his prestige. This is malicious conduct, that is, it is done with the knowledge that it will cause damages.
As an exception to this type of crime, those slanders or insults that are carried out against public officials will be prosecuted ex officio, provided that they allude to facts related to their functions.