The Latin maxim ex post facto literally translates to ‘arising from past facts’ or ‘out of the aftermath’. In the legal scenario, the ex post facto law can retroactively change the legal consequence of an action that was committed before the enactment of the law and was considered lawful in the past.
However, there have been objections to this law as it is seen as a violation of the rule of law, and many constitutional democracies have safeguards against it. Article 20 (1) of the Constitution of India enshrines the judicial right of a person to not be convicted of an offence that did not violate the law at the time that it was committed, while immunizing the person against an enhanced penalty than that incurred when convicted, acting effectually as a prohibition to the ex post facto law.
With reference to the Rattan Lal v. State of Punjab case, the boy charged with the offence of outraging the modesty of a girl and trespassing was sentenced to six months of imprisonment. Meanwhile, with the enforcement of the Probation of Offenders Act, 1958, stating that an individual below the age of twenty-one years cannot be imprisoned. With regard to this Act, the accused pleaded that he be considered under the provisions of the reformed Act. This plea was dismissed citing that it was an ex post facto law, although, prohibition to ex post facto laws when beneficial to the accused does not fall under the ambit of Article 20 (1).
An exception to the prohibition, and a relevant case for the ex post facto law is that of Jawala Ram v. the State of Pepsu. There was a retrospective imposition of special rates for the unauthorised use of canal water in this scenario, not impinged by Article 20 (1).
Ex post facto laws have been considered a privilege for legislators, however, in the present scenario, apex courts play a significant role in preventing the abuse of the law, and protecting the rights of the people.