The concept of justice is at the center of current discussions of political philosophy. Hans Kelsen, perhaps the most important twentieth century jurist who worked the concept from perspectives that remain neglected today. The scant attention that has received the relativistic concept of justice held by Kelsen tends to impoverish the discussion on Justice today. This is why it is undertaken here rereading Kelsen’s work around the concept mentioned. So, a couple of errors are displayed in their argument, not naturally attributable to their inability but his eagerness to refute the views of Justice he criticized in this paper ‒ which we call ‘impossible justices’‒. Particularly the difficulty of his argument against Plato is reviewed and special attention is given to some contradictory implications of the concept of ‘Justice of tolerance’, which operates as a corollary of his thoughts on the matter.