Doctoral Thesis / Dissertation from the year 2023 in the subject Law - Tax / Fiscal Law, University of Strasbourg (Centre for International and European Studies), course: European Tax Law, language: English, abstract: The thesis addresses the challenge to compare both the CJEU and the ECtHR case-laws dealing with issues concerning the taxpayers' procedural rights. Those courts faced the same difficulty to guarantee the European taxpayers' rights while neither the EU Founding Treaties, nor the European Convention on Human Rights include stipulations with sheer fiscal purpose. However, despite that apparent mutism, the Convention and EU law turn out today to be fundamental sources in the field of taxation. Similarly to the CJEU, who impelled the Member States to direct taxation "downward harmonisation", the ECtHR set up a constructive case-law, which unveiled fiscal perspectives over stipulations that have not been conceived originally under such conception. The thesis is focused on the contributions both European courts delivered in the field of taxpayers' procedural safeguards and investigates into the existence of a common corpus: all taxation phases are thus covered, regardless of whether it is in the stage of tax base assessment, tax liquidation or tax collection, but as well and mostly so regarding the administrative oversight and prospective sanctions that could result from. The thesis overpasses its initial scope in order to examine legal tools and reasoning patterns European justices in both courts have put in place in order to give rise to taxpayers' real procedural safeguards.