This article raises the importance of the thoughts made about the proof from philosophicalpolitical and epistemological perspectives. Also raises the two main aspects of the evaluation evidence: validity and credible. Validity is a topic that leads to study, mainly from the political philosophy, the relationship between the individual and the State because the proof since its obtaining and evaluation have the potential to affect the person in all his life aspects: physical, psychological and social, so a wrong method on the obtaining and evaluation may lead to harm fundamental rights. In the other hand, the credible evalution involves, mainly, epistemological reflections about the truth of the facts. We analyze the truth by correspondence as the ideal. Also, we study the concept of consensual, coherence and pragmatist truth, wich are theories that have been used to deny, precisely, the truth.