While the existence of monitoring, reporting and fact-finding (MRF) bodies in the international realm is not a new phenomenon, the recent proliferation of such institutions raises a number of policy and legal issues. One issue is that, as MRF bodies are increasingly called to make legal determinations and interpret existing unsettled rules or concepts of international law, these mechanisms’ role and practice in this regard attract more legal scrutiny. As a result, the way that MRF missions apply the law — as much as the methodology used to establish facts — can affect the mission’s credibility. This paper addresses this issue by focusing on the selection and application of legal lenses in MRF mechanisms. The paper aims at describing and analyzing the current practice to identify strengths, gaps, and challenges, with a view to presenting options to improve the ways that MRF practitioners articulate and apply legal frameworks.