The ex post facto law or also known as retroactive law is a bylaw that retroactively changes a particular legal consequences or status of a specific actions and relationships that are committed prior to enactment of the directive. As an example, for criminal law the ex post facto works by criminalizing the actions that were legally identified when committed. It may also works by aggravating a crime thru bringing it into extreme categories when it was committed. This law may also work by increasing or changing the punishment that are required or sentence for a crime. They may extend the terms of punishment or may add more penalties.