Explanation: An ex facto is a law that declares someone’s action to be criminal only after it was committed, ex post facto law is considered a hallmark of tyranny because it deprives people of a sense of what behavior will or will not be punished and allows for random punishment at the whim of those in power. It is most typically used to refer to a criminal statute that punishes actions retroactively, it thereby criminalize an action conduct that was legal when it was originally performed. It is a law that criminalizes a conduct that was not criminal when performed, it is used to increase punishment for crimes already committed
