Retroactivity of criminal law

We must refer to the statute of limitations in criminal matters, which constitutes a limit to ius puniendi, a limit that the states themselves set. The statute of limitations cannot be conceived of as a right of the person responsible for an offence, but as a self-limitation of the punitive power of the state. This affirmation is evident in that the statute of limitations cannot be waived for the accused, as the political-criminal grounds for the statute of limitations, of a social order, are above the interest of the accused in proving his innocence. In practice, the statute of limitations is an institute that releases the responsibility that arises from the commission of the crime, through the passage of a certain period of time that ends the right of the State to impose the penalty. It is a cause of extinction of criminal liability that acts after the commission of the offence, extending over the penalty. Non-applicability of statutes of limitation can be perfectly explained from a conception of criminal law as a necessary instrument to preserve a certain social order, when it comes to crimes such as those against humanity, as their prosecution and punishment continue to be necessary as long as the perpetrators are alive.