The Calcutta High Court has held that penal provisions of the Aadhaar Act cannot be applied retrospectively without an express legislative provision, as such retroactive penal application is barred by Article 20(1) of the Constitution. The ruling addresses challenges to Regulation 28A of the Aadhaar (Enrolment and Update) Regulations, 2023, which allows deactivation of Aadhaar cards issued to foreign nationals. The court emphasised that unless Parliament explicitly states otherwise, amendments imposing penalties cannot affect past actions—reinforcing the protection against ex post facto laws.

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