Assuming that Justice is the most important problem of law's philosophy, this study comes to investigate whither Hans-Georg Gadamer tought, a german philosopher, can contribute in this regard, especially considering the moment of Law's interpretation and application. To Our view, the ideas of "The Grand Old Man of Philosophy", lead us, first, to the unwavering conclusion that there is no possibility of a single interpretation objectively tenable, on the grounds that legal phenomenon cannot be encompassed by law. However, Kelsen had already shown us that a long time ago. Furthermore, it is intended to bring to light, that, who comes to mind with law's philosophy, more specifically with interpretation and law application, cannot ignore some topics as language, pre-understanding and tradition. More than that: for us, Gadamer, especially through the analysis of Aristotelian phronesis, reveal us the idea that legislate, act and apply the standard to an individual case, according to politics, ethics and law's interpretation and application function, pass necessarily through the notion of "good decision" being inseparable things and from the same ethos and, rather than being satisfied with epistemological solutions, we should try to establish an ontological solution, in order to enable a higher control of justice failure in concrete cases, revealed for us by the approach of "is" and "ought".