Keywords: Ne Bis in Idem Principle; European Court of Human Rights' Case Law; Notion of "Criminal Matter"; Dual-Track Penalty System.
This essay analyzes the European Court of Human Rights' case law concerning the ne bis in idem principle, as enshrined in Article 4 of Procol No. 7 to the ECHR. The purpose is to point out certain elements of that case law that may seem unclear or even contradictory. After clarifying the content of the principle in the Council of Europe's system, this paper focuses especially on the origin and development of the notion of "sufficiently close connection in substance and in time" between criminal and administrative proceedings, in the light of some recent judgments delivered in cases related to dual-track penalty systems. The author argues that the use of that notion seems to be meant to ensure the proportionality of the penalty system, rather than prohibiting the duplication of "criminal" proceedings, thus significantly changing the nature and the aim of the principle.