Article 20 of Indian constitution grants protection against arbitrary and excessive punishment to an accused person, whether citizen or foreigner or legal person like a company or a corporation. It contains three provisions in that direction:
- No ex-post-facto law: No person shall be (i) convicted of any offence except for violation of a law in force at the time of the commission of the act, nor (ii) subjected to a penalty greater than that prescribed by the law in force at the time of the commission of the act.
- No double jeopardy: No person shall be prosecuted and punished for the same offence more than once.
- No self-incrimination: No person accused of any offence shall be compelled to be a witness against himself.
An ex-post-facto law is one that imposes penalties retrospectively (retroactively), that is, upon acts already done or which increases the penalties for such acts. The enactment of such a law is prohibited by the first provision of Article 20. However, this limitation is imposed only on criminal laws and not on civil laws or tax laws. In other words, a civil liability or a tax can be imposed retrospectively. Further, this provision prohibits only conviction or sentence under an ex-post-facto criminal law and not the trial thereof. Finally, the protection (immunity) under this provision cannot be claimed in case of preventive detention or demanding security from a person.
The protection against double jeopardy is available only in proceedings before a court of law or a judicial tribunal. In other words, it is not available in proceedings before departmental or administrative authorities as they are not of judicial nature.
The protection against self-incrimination extends to both oral evidence and documentary evidence. However, it does not extend to (i) compulsory production of material objects, (ii) compulsion to give thumb impression, specimen signature, blood specimens, and (iii) compulsory exhibition of the body. Further, it extends only to criminal proceedings and not to civil proceedings or proceedings which are not of criminal nature.