Ex post facto law

Also called: Article 20(1), Retrospective criminal law · Topic: Fundamental Rights and Constitutional Remedies · NCERT: Class 11, Ch 2 "Rights in the Indian Constitution"

Meaning

An ex post facto law is a law that reaches back in time and punishes an act done before the law was made. Article 20(1) bars this for criminal law in two ways:

• No one can be convicted for an act that was not an offence when it was done.
• No one can get a heavier penalty than the law allowed at the time of the act.

It matters because people must be able to know, at the moment they act, whether that act is a crime and what the punishment can be. Without this, the State could punish people for acts that were legal when they did them.

Explanation

How Article 20(1) works

• The basic rule: a person can be convicted only for breaking a law that was in force when the act was done.
• Two bars in one clause:
• Bar on new offences reaching back. If an act was legal on the day it was done, a later law cannot make it a crime for that person.

• Bar on a heavier penalty reaching back. If the law allowed a smaller punishment on the day of the act, a later law cannot raise that person's punishment.

• Who it protects: every person. This includes citizens, foreigners and companies.

• Where it sits: it is one of three shields in Article 20 (protection in respect of conviction for offences). NCERT calls these the "rights of the accused".

What it does NOT cover (limits)

• Only criminal laws. Civil laws and tax laws can be retrospective, which means they can apply to past periods.

• For example, Parliament may change a tax rule for an earlier period. Article 20(1) does not stop this, because a tax is not a criminal penalty.

• Only conviction and sentence. It does not bar a trial under a new procedure.

• A new law can change how a trial is run (the procedure) and still apply to acts done earlier.

• It cannot create the offence or raise the penalty after the act.

• Changes that help the accused can reach back.

• If a new law gives a lighter penalty, the accused can get its benefit even for a past act (Rattan Lal v. State of Punjab, 1965).
• The clause protects the accused. It does not stop the State from being kinder.

Protection during Emergency

• During a National Emergency, the President can suspend the court enforcement of many Fundamental Rights (Article 359).
• The 44th Amendment, 1978 says Articles 20 and 21 cannot be suspended, even during an Emergency.
• So the bar on ex post facto criminal law holds even in the most serious national crisis.

In the Constitution and practice

• Constitutional home: Article 20(1), in Part III (Fundamental Rights, Articles 12-35) of the Constitution, in force since 1950.
• Who it binds: the legislature (it cannot pass such laws) and the courts (they cannot convict or sentence under them).
• Key amendment: the 44th Amendment, 1978 made Article 20 non-suspendable during a National Emergency (Article 359).
• Landmark case:

• Rattan Lal v. State of Punjab (1965): a change in law that helps the accused, such as a lighter penalty, can apply to past acts.

• How it works when criminal laws change:

• The Bharatiya Nagarik Suraksha Sanhita (BNSS), 2023 replaced the CrPC and came into force on 1 July 2024. It is a procedural law, which means it sets out how arrests, bail and trials are run.
• Because Article 20(1) does not bar a new procedure, procedural changes can apply to old cases.
• BNSS s. 479 lets an undertrial get bail after serving half of the maximum term. A first-time offender gets release on bond after one-third [2].
• In 2024, the Supreme Court said s. 479 applies to all undertrials, including those whose cases were registered before 1 July 2024 [3]. This follows the same idea as Rattan Lal: a change that helps the accused can reach back.

Don't confuse with

• Retrospective civil or tax law: these are allowed. Article 20(1) bars only retrospective criminal conviction and penalty.
• Double jeopardy (Article 20(2)): this bars being prosecuted and punished twice for the same offence. Article 20(1) is about when the law was made, not about how many times a person is punished.
• Right against self-incrimination (Article 20(3)): this bars forcing an accused to be a witness against themselves. It has nothing to do with the timing of the law.
• Preventive detention (Article 22(4)-(7)): this means jailing a person without trial to stop a feared future act. Article 20(1) deals with punishment for a past act, judged by the law of that time.

Prelims Hooks

• Article 20(1) bars two things: conviction under an ex post facto criminal law, and a heavier penalty than the law allowed when the act was done.
• Trap: Article 20(1) covers criminal laws only. Civil and tax laws can be retrospective.
• Trap: Article 20(1) does not bar a trial under a new procedure. It bars only retrospective conviction and sentence.
• Rattan Lal v. State of Punjab (1965): a lighter penalty brought in later can benefit the accused for a past act.
• 44th Amendment, 1978: Articles 20 and 21 cannot be suspended during a National Emergency (Article 359).
• Article 20 protects every person: citizens, foreigners and companies.

Mains Points

• Rule of law and fair warning:
• Article 20(1) means a person can be punished only under a law they could have known at the time they acted.

• Because the 44th Amendment, 1978 made it non-suspendable, this protection holds even during an Emergency. That makes it one of the firmest guarantees in Part III.

• Where the line is drawn (criminal vs civil or tax):

• Parliament keeps the power to pass retrospective civil and tax laws. This lets it fix gaps in a law or protect public revenue.

• Critics say retrospective tax changes still hurt certainty for citizens and investors, even though they are constitutional. Reform options include using such power rarely and giving clear reasons for it.

• New criminal laws and old cases:

• When criminal law is rewritten, as with the BNSS, 2023 (in force from 1 July 2024), Article 20(1) lets procedural changes apply to pending cases. It forbids new offences or harsher penalties from reaching back.
• Changes that help the accused can apply to past cases. Examples are Rattan Lal (1965) and the Supreme Court applying BNSS s. 479 to undertrials whose cases were registered before 1 July 2024 [3]. This shows that Article 20(1) protects the accused and does not stop the State from showing mercy.

Related concepts

• Protection in respect of conviction for offences
• Double jeopardy
• Right against self-incrimination
• Narco-analysis test
• Protection against arrest and detention
• Right to speedy trial
• D.K. Basu guidelines
• Preventive detention
• Advisory board
• National Security Act 1980

Read more

• Rights of the accused and detenus: Articles 20 and 22, and the NHRC