Article 20 for CLAT: Ex Post Facto, Double Jeopardy

📑 On this page

⚡ The short answer

Article 20 gives every accused person three shields. No ex post facto punishment: you're judged by the criminal law in force when you acted. No double jeopardy: no second prosecution and punishment for the same offence. No self-incrimination: an accused can't be forced to testify against himself. Physical evidence like fingerprints or blood isn't covered.

🎬 The 30-second story

The scooter summer

“Renting my scooter to tourists all May. Easy money!”

🛵

Aarav

In May, this is perfectly legal.

“From 1 August, renting a private vehicle is a crime.”

📰

In August, a new law arrives.

“You rented in May. You're under arrest. Sign this confession.”

📝

The police come knocking.

“It was legal in May! And I'm not signing.”

⚖️

Aarav

Tara's ruling: Aarav can't be convicted for May: a crime must be a crime when you commit it. Nor can he be forced to confess. But rent in September and he's caught, and police can still take his fingerprints.

What does Article 20 protect you from?

Criminal law is where the State can lock you up, so the Constitution limits that power three ways. The shields protect every person, citizen or foreigner, in criminal matters, and survive even a national Emergency.

🧩 At a glance

The three shields

⏪No ex post facto punishment

No conviction under a law made after the act; no punishment heavier than the one then in force.

2️⃣No double jeopardy

No one is prosecuted and punished twice for the same offence.

🤐No self-incrimination

A person accused of an offence can't be compelled to be a witness against himself.

A CLAT passage puts it plainly: 'nobody can be punished twice for the same offence.' Each shield has trigger words. Check that the facts fit every one.

📌 What CLAT actually expects

The passage gives the rule. Test the facts against its words: when was the act, was there a court punishment, was he accused yet, and was it testimony or a sample?

How do you test an Article 20 claim?

🧭 Decision flow

Does Article 20 save the accused?

❓ What is the complaint?

A law made after the act →

❓ Does the new law create a crime or raise the punishment?

Yes →

Shield applies: old law governs

No →

New law can apply

Procedure, civil liability or a lighter sentence.

A second case →

❓ Was he earlier prosecuted and punished by a court?

Mobs and departmental inquiries don't count.

No →

Article 20 doesn't bar it

Acquittals are covered by criminal procedure law instead.

Yes ↓

❓ Is it the same offence (same ingredients)?

Yes →

Second case barred

No →

Different offence: allowed

Forced to give evidence →

❓ Was he formally accused at the time?

An FIR or complaint naming him.

No →

Not yet accused: no shield

Yes ↓

❓ Was he forced to give testimony?

Fingerprints, blood and voice samples aren't testimony.

Yes →

Shield applies: evidence barred

No →

Physical or voluntary: allowed

When can a new law not punish you for an old act?

An ex post facto law reaches back 'after the fact'. Article 20 blocks two kinds: a law making an act a crime after it was done, and one increasing the punishment afterwards. A third kind, a new procedure for old offences, passes.

⚔️ Side by side

What the first shield blocks, and what it lets through

🛑Blocked

retrospective criminal harshness

•A new crime applied to past acts
•A longer term or bigger fine for a past offence
•Simple imprisonment made rigorous

✅Allowed

everything else

•A new procedure or special court
•A lighter punishment
•Retrospective tax or civil liability

Test	Blocked	Allowed
Scooter example	Jail for May rentals	A fast-track court for August cases

The test is criminal harshness, not retrospectivity as such.

What if the new law is kinder?

The shield protects the accused, not the State, so a law that softens punishment can reach back to help him. In Rattan Lal, a 16-year-old got the benefit of a probation law that arrived after his conviction.

Is every retrospective law banned?

No. The words are 'convicted of any offence' and 'penalty', so the shield lives inside criminal law. Parliament can tax retrospectively, change civil liabilities backwards or create a new court for old cases. Nobody has a vested right to a procedure.

When is a second case double jeopardy?

🧮 The formula

All four, or no shield

⚖️

Earlier case before a court

or a judicial tribunal

🔒

Prosecuted AND punished

both, not either

🧩

Same offence

same ingredients

🔁

Fresh prosecution

not an appeal

🛡️

Second case barred

The Indian version is narrow. The American rule bars a second trial even after an acquittal; Article 20 needs prosecution and punishment. Acquittals are protected separately by ordinary criminal procedure law.

✓Mob justice isn't punishment. Only a court can 'punish'.
✓Departmental action isn't prosecution. A dismissed official can still be tried (S.A. Venkataraman).
✓Same act, different offences with different ingredients can both be tried.
✓An appeal isn't a second case. A State appeal against acquittal continues the first prosecution (Kalawati).

What does 'compelled to be a witness against himself' cover?

Break the shield into parts. The person must be accused when the evidence is taken. There must be compulsion. And he must be made 'to be a witness': passing on what he knows, by speaking or writing. Miss one and the shield drops.

🎚️ The scale

Physical evidence vs testimony

← Police can take itShielded →

Body marks

Fingerprints, photos

e.g. no memory involved

Samples

Blood, DNA, handwriting, voice

e.g. voice samples can be ordered (Ritesh Sinha)

Voluntary words

A confession given freely

e.g. no compulsion, so no shield

Forced answers

Police questioning

e.g. right to silence (Nandini Satpathy)

Mind-reading

Forced narco, polygraph, brain-mapping

e.g. barred (Selvi)

The shield isn't only for court. In Nandini Satpathy, a former Chief Minister refused to answer police questions; the right to silence was held to reach police interrogation, and answers that could expose you to other charges.

⚠️ Suspect is not accused

'Person accused' means an FIR or complaint names you. Being stopped and questioned on suspicion isn't enough, and statements made before the accusation don't become protected later.

Which Article 20 cases should you know?

🪙

Landmark case · 1953 · Supreme Court

Maqbool Hussain v State of Bombay

📋

What happened

A passenger landed in Bombay in 1949 with about 107 tolas of undeclared gold. Customs confiscated it; then he was prosecuted under foreign exchange law for the same import.

❓

The question

Did the confiscation bar the criminal case?

🔨

What the court held

No. Customs officers aren't a court or judicial tribunal, and confiscation isn't punishment in the Article 20 sense.

What CLAT takes from it: The first round must be criminal proceedings before a court.

✍️

Landmark case · 1961 · Supreme Court (11 judges)

State of Bombay v Kathi Kalu Oghad

📋

What happened

Police took specimen handwriting and thumb impressions from accused persons in custody to prove their guilt.

❓

The question

Does that make the accused 'a witness against himself'?

🔨

What the court held

No. Being a witness means passing on personal knowledge; a fingerprint only gives material for comparison. The person must also have been accused when he made the statement.

What CLAT takes from it: Testimony is protected; physical evidence isn't.

🧠

Landmark case · 2010 · Supreme Court

Selvi v State of Karnataka

📋

What happened

Accused persons, suspects and witnesses were made to undergo narcoanalysis, polygraph and brain-mapping tests without consent.

❓

The question

Physical evidence like blood, or forced testimony?

🔨

What the court held

Forced testimony. Involuntary tests violate Article 20(3) and personal liberty under Article 21. Voluntary tests are allowed with safeguards.

What CLAT takes from it: Pulling out what's in your mind is compulsion to testify, however scientific.

🕊️

Landmark case · 1964 · Supreme Court

Rattan Lal v State of Punjab

📋

What happened

A 16-year-old was convicted of house trespass. A probation law reached his district only after the conviction.

❓

The question

Can the later law help him?

🔨

What the court held

Yes, by majority. A law that only softens criminal law isn't caught by the ex post facto bar.

What CLAT takes from it: The first shield blocks harsher retrospective laws, never kinder ones.

How has CLAT asked Article 20?

📝 Asked in CLAT 2018 · Q165 Double jeopardy

Legal Principle: The Latin maxim nemo bis punitur pro eodem delicto means that nobody can be punished twice for the same offence. Fact Situation: Sajan, a petty thief, is caught and thrashed thoroughly by the people before being handed over to the police. Sajan pleads before the magistrate that since he was already thrashed by the people he should not be again punished by the State.

Which of the following statements is the most appropriate in relation to the legal principle stated above?

ASajan is right since nobody should be punished for the same offence twice.

BThrashing given by the people does not amount to legal punishment and so Sajan can be punished by the State.

CGiving a good thrashing to the thief is the best form of punishment to prevent future theft.

DThe Magistrate should take into consideration the thrashing received by Sajan while fixing his punishment.

Reveal answer + reasoning

Answer: B

'Punished' means punished by law after a prosecution. A crowd isn't a court, so this is Sajan's first prosecution. (Options were numbered 1–4; key: 2.)

Why the others fail

A — Treats a beating as legal punishment.
C — A policy opinion, not the principle.
D — Humane, but the question is whether he can be punished at all.

📝 Asked in CLAT 2018 · Q171 Self-incrimination

Legal Principle: Article 20(3) of the Constitution of India states that no person accused of any offence shall be compelled to be a witness against himself. Fact Situation: Ubaid refuses to give a sample of his blood after he is stopped by the police for driving over the speed limit. The police suspect him to be driving under the influence of alcohol, which is prohibited under the law.

Which of the following statements is the most appropriate in relation to the legal principle stated above?

AUbaid is protected by Article 20(3) in his refusal to give a blood sample.

BUbaid is not protected by Article 20(3) as he was under the influence of alcohol.

CUbaid is not protected by Article 20(3) in his refusal to give a blood sample since he is not accused of any offence yet.

DRefusal to give a blood sample is a crime and Ubaid must be punished for the same.

Reveal answer + reasoning

Answer: C

Trigger word: 'accused'. Ubaid has only been stopped on suspicion, so the shield isn't engaged. Real law agrees for a second reason: blood is physical evidence, not testimony (Kathi Kalu Oghad). (Key: 3.)

Why the others fail

A — Assumes he's an accused.
B — His drinking is unproven and beside the point.
D — The principle says nothing about punishing a refusal.

📝 Asked in CLAT 2020 · Q102 Ex post facto laws

Article 20(1) of the Indian Constitution prohibits Ex Post Facto laws… Ex post facto laws are of three kinds as follows: (a) A law which declared some act or omission as an offence for the first time after the completion of that act or omission. (b) A law which enhances the punishment or penalty for an offence subsequent to the commission of that offence. (c) A law which prescribes a new and different procedure for the prosecution of an offence subsequent to the commission of that offence. Clause (1) of Art. 20 provides protection only in respect of the above first two categories…

Article 20 (1) would not affect which of the following acts of the legislature?

AAct of the legislature enhancing the term of imprisonment.

BAct of the legislature enhancing the amount of fine.

CAct of the legislature changing the punishment of death to life imprisonment.

DAct of legislature changing the nature of imprisonment from simple to rigorous.

Reveal answer + reasoning

Answer: C

The shield stops heavier punishment after the act. Death to life imprisonment is lighter, so Article 20(1) doesn't block it.

Why the others fail

A — An enhanced penalty: blocked.
B — A bigger fine is enhancement too.
D — Rigorous is harsher than simple.

Also asked: CLAT 2020 Q104–105 applied a later juvenile-age change and a probation benefit to a past act: both allowed. CLAT 2023 Q69 let a new law award compensation for past conduct, treating it as civil, not penal.

⚠️ A key worth arguing with

In CLAT 2020 Q103, a blog posted before a hate-speech offence existed was charged under it. The key (A) says he may be liable because the blog stayed up, a continuing act. On a strict Article 20(1) reading, C looks stronger. Know the key and the dispute.

Can you dodge these Article 20 traps?

💥 Myth vs fact

Traps students fall for

🙅 Myth

Article 20 protects you from a second trial after an acquittal.

Tap to bust it →

✅ Fact

It needs prosecution and punishment. The bar after acquittal comes from criminal procedure law.

🙅 Myth

Every retrospective law is unconstitutional.

Tap to bust it →

✅ Fact

Only those that create crimes or raise punishment. Tax, civil liability, procedure and lighter sentences can reach back.

🙅 Myth

You can refuse fingerprints or a blood test under Article 20.

Tap to bust it →

✅ Fact

Physical evidence isn't 'being a witness'. Only testimony is shielded.

🙅 Myth

The right to silence starts in court.

Tap to bust it →

✅ Fact

It reaches police interrogation (Nandini Satpathy).

🎯 Quick quiz

Five fact patterns, three shields

0 / 5

Rohan cheats in March. In June, a new law moves such cases to a fast-track court with a shorter procedure; the punishment is unchanged.

Q1. Can Rohan insist on the old procedure?

A government clerk is dismissed after a departmental inquiry into a bribe, then prosecuted for it.

Q2. Is the prosecution double jeopardy?

Kabir, named in a fraud FIR, is drugged for a narcoanalysis test without consent.

Q3. Can his answers be used against him?

Aarav's offence carried 7 years when committed. Before sentencing, the law cuts it to 3.

Q4. Which sentence can apply?

Suppose the rule says: 'No person shall be tried twice for the same offence, whether convicted or acquitted.' Zoya is acquitted of theft; the State files a fresh case for it.

Q5. Under this rule?

🎯 Article 20 in a nutshell

Three shields for every accused, in criminal matters only, never suspended.
Ex post facto: no new crime or heavier punishment for a past act.
Double jeopardy: a court's prosecution and punishment for the same offence.
Self-incrimination: accused + compelled + testimony. Fingerprints and blood aren't testimony.
Forced narco tests are out; silence in police questioning is in.

📎 Good to know, not to memorise

Article 20(1) ex post facto, 20(2) double jeopardy, 20(3) self-incrimination. Article 359, after the 44th Amendment (1978), protects Articles 20 and 21 in an Emergency.
Retrial bar after acquittal or conviction: CrPC s.300, now BNSS 2023 s.337.
BNS 2023 s.358 keeps pre-1 July 2024 offences under the IPC.
The Criminal Procedure (Identification) Act 2022 widened the samples police can take.
Also: Nandini Satpathy (1978), Ritesh Sinha (2019).

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Frequently asked questions

What are the three protections under Article 20?

No conviction under a criminal law made after the act, and no heavier punishment than the law then allowed; no second prosecution and punishment for the same offence; and no forcing an accused person to be a witness against himself.

Can a law reduce the punishment for an offence already committed?

Yes. Article 20 blocks only laws that create a crime or raise the punishment after the act. A law that softens punishment, like death to life imprisonment or a probation benefit, can apply to past offences, as in Rattan Lal v State of Punjab.

Is a departmental inquiry followed by a criminal case double jeopardy?

No. Double jeopardy under Article 20 needs an earlier prosecution and punishment by a court or judicial tribunal for the same offence. An internal inquiry at work isn't a criminal prosecution, so an employee can be dismissed and also tried in a criminal court for the same conduct.

Can the police force me to give fingerprints or a blood sample?

Yes. In Kathi Kalu Oghad the Supreme Court held that fingerprints, thumb impressions and specimen handwriting are physical evidence, not testimony, so Article 20 doesn't cover them. Being a witness means passing on what you personally know. A magistrate can also order a voice sample.

Are narco tests legal in India?

Only with consent. In Selvi v State of Karnataka, the Supreme Court held that forcing narcoanalysis, polygraph or brain-mapping tests violates both the right against self-incrimination and personal liberty. Voluntary tests are allowed with safeguards, but their results alone aren't evidence.