International criminal law has the viability necessary of using universal jurisdiction as a valuable tool to avoid impunity in the face of crimes that attack all humanity committed in the in the midst of ongoing armed conflicts. The principle of universal jurisdiction allows justice to be done by any international tribunal, regardless where those crimes will be held, the nationality of the perpetrators or participants or who were the victims, provided that they are crimes that affect the international community. One of the concerns of the actors that were part of the non-international armed conflict that has happened for decades in Colombia is the issue of legal security contained in the agreements between the Revolutionary Armed Forces of the People's Army (FARC-EP) and the Colombian government, specifically, when applying transitional justice. The anxiety produced by that the application of this type of justice is not given in such a way that any court in the world can initiate criminal proceedings for the same facts, is certainly founded. It is known that when a conflict ends (or as it happened in Colombia without finishing it), the parts of it look for negotiated solutions to reach peace agreements. At that time, the so-called transitional justice emerged as the main solution to justice issues, which granted great benefits to the parts mentioned and also to society in general. This research poses the difficulties of using the Principle of Universal Jurisdiction in the Colombian post-conflict context, in addition, it explores the solutions in which national and international doctrine and jurisprudence have reached regarding of criminal legality principle and as the application of international criminal law, what includes universal jurisdiction, does not violate criminal law as such. With this objective and to solve these purposes, in short, the article might allow us to conclude with a proposal specifically addressed to Colombia in order to avoid tension between the PJU and legal security in the midst of transitional justice in Colombia. [ABSTRACT FROM AUTHOR]