Article 20 of the Constitution India made up of 3 clauses and cannot be set aside even during an emergency. Also, it guarantees protection to both citizens and non- citizens.
Article 20 provides the legal principles of the Criminal jurisprudence, which are detailed in the three clauses, i.e. Ex-post facto law, Doctrine of Double Jeopardy and Prohibition against self-incrimination.
Protection against Ex post facto law: Article 20(1)
Article 20 (1) states that
- No person shall be convicted of any offence except for violation of the law in force at the time of the commission of the act charged as an offence.
- And also no person shall be liable penalty greater than that which might have been inflicted under the law in force at the time of the commission of the offence.
So, mainly this provision entails a ceiling on law making power of legislature as this provision wipes out the chance of retrospective implementation of criminal laws or prohibits retrospective implementation of a law having criminal nature.
In the case of Kedar Nath v. State of West Bengal  the Hon’ble Supreme Court of India held that “whenever an act is declared as a criminal offence and/or provides penalty for same by the legislature, it is always prospective in nature and can’t be implemented retrospectively to uphold what is being said under Article 20 (1)”.
In another case, Mohan Lal v. State of RajasthanCourt held that “conviction and/or punishments under an ex post facto law is prohibited under Article 20 and not the trial or prosecution itself. Also, trial under a different procedure than what existed during the commission of the act doesn’t come under the ambit of the same and can’t be struck down as unconstitutional”.
However, the Hon’ble Supreme Court in the case of Rattan Lal v. the State of Punjab provided an exception to the restriction under this clause. In this case, the Court allowed retrospective implementation of Criminal Laws, where there was a decrease in punishment in the said offence.
Exception of Article 20(1)
- Protection against Ex post facto laws is only available in criminal cases and not in civil cases.
- Retrospective implementation of Criminal Laws can be done where there is a reduction in punishment.
- Protection against ex post facto laws under Article 20 is only in respect of substantive laws and not in case of procedural laws.
Double jeopardy: Article 20(2)
“Nemo debet bis vexari pro una et eadem causa”
The Doctrine of Double Jeopardy means ‘no person can be prosecuted and punished twice for the same offence in subsequent proceedings’ and Article
In short, Article 20 (2) guarantees protection against multiple convictions for the same offence.
The most essential landmark judgement on Article 20 (2) was pronounced in the case of Maqbool Hussain v. State of Bombay, the person accused in this case possessed some gold, which was against the law of land at the time, therefore, was seized by the customs authority. And, afterwards, when he was prosecuted before a criminal court, the question, in this case, arose that whether this amounts to Double Jeopardy.
The Supreme Court, in this case, observed that “departmental proceedings, i.e. by Customs Authority, in this case, doesn’t amount to trial by a judicial tribunal, thus the proceedings before the criminal court is not barred in this case and the proceedings can go on”.
Prohibition against self-incrimination: Article 20(3)
This clause provides for the prohibition against Self-incrimination. It states no person accused of any offence shall be compelled to be a witness against himself. The prohibition against self-incrimination could only be exercised if the person is accused of a criminal offence
In M.P. Sharma v. Satish Chandra the term ‘Witness’ was described, it was held that the term Witness incorporates both, Oral and documentary evidence. The Court also stated that however, there is no restriction where a search and seizures of the document is being done by the authorities. Though, the evidence produced willingly by the accused is acceptable.
The Hon’ble Supreme Court in Narayanlal vs Maneck, held “that to claim the immunity from being self-incriminated, there must exist a formal accusation against the person and mere general inquiry and investigation don’t form grounds for the same”.
 1953 AIR 404, 1954 SCR 30
 AIR 2015 SC 2098
 1965 AIR 444, 1964 SCR (7) 676
 1953 AIR 325, 1953 SCR 730
 1954 AIR 300, 1954 SCR 1077
 1961 AIR 29, 1961 SCR (1) 417