Lex mitior à prova - ação de improbidade e direitos humanos: garantias processuais convencionais versus a modulação do Tema 1.199 DO STF

Abstract

This study examines whether the temporal modulation adopted by Brazil’s Supreme Federal Court (STF) in Leading Case 1.199, which restricts the retroactive application of Law 14,230/2021 to pending administrative-improbity actions, complies with Articles 8 and 9 of the American Convention on Human Rights (ACHR), a norm of supra- statutory status in Brazilian law. It starts from the premise that the sanctions set forth in Law 8,429/1992 (removal from public office, suspension of political rights, and substantial fines) are punitive in nature and therefore attract the full range of conventional criminal guarantees, including the lex mitior principle. The research employs a doctrinal-legal methodology, supplemented by comparative analysis of case law from the European Court of Human Rights (Engel, Öztürk) and the Inter-American Court (Baena Ricardo, Rosadio Villavicencio). The study shows that, by prioritizing res judicata, the STF failed to apply the “double vertical compatibility” required by the ACHR and disregarded Inter-American precedents that mandate review of final judgments whenever a subsequent, more lenient law applies. It concludes that Thesis 2 of Leading Case 1,199 violates Article 9 of the ACHR, exposing Brazil to potential international liability, and suggests two harmonization paths: internal revision of the STF’s modulation or the exercise of diffused conventionality control by domestic courts