1 Children from different parents: the challenge of vivre ensemble in a world of arbitrators and constitutional judges Marcelo Lozada Gomez 1 Abstract The present research focuses on the relationship between constitutional judges and investment arbitrators. In particular, it addresses the increasing substantive overlap between the classical jurisdiction of the former and the expansive scope of adjudication of the latter, in view of recent developments in the way investors tend to bring claims before international arbitrators in order to challenge decisions made by constitutional judges, even those highly complex cases where the guarantee of constitutional values or the enforcement of international obligations belonging to different regimes of international law is at stake. In light of this reality, the text undertakes an analysis of four cases that will allow the reader to assess existing scenarios of this relationship, and the absence of tools through which both judges and arbitrators may vivre ensemble. This research is an academic appetizer that sheds some light on this discussion that may reasonably be given more importance in the upcoming years. 1 Lecturer in Constitutional law. Universidad Externado de Colombia