• Law is a system of binding rules, statutes, and principles enforced by governmental or social institutions to regulate behaviour, maintain order, and ensure justice within a society.
• A rule is an official instruction, regulation, or principle guiding behaviour, methods, or procedures in games, society, and organizations.

What is ex post facto?

• A person can only be convicted for a crime which is punishable under a law that is valid at the time the crime is committed.
• Article 20 prohibits the imposition of enhanced penalty or punishment. But it does not bar any reduction in the punishment.
• validity of the law is not challenged here, but only conviction under the law.

Facts you need to know

• The said article seeks to safeguard and protect the rights of those persons who are accused of any crime and includes citizens, non- citizens as well as corporations.
• Cannot be suspended even during an emergency declared under article 359.

Source: The Hindu