Over the years and most recently, various conflict/crisis situations including those in Chad, Democratic Republic of Congo (DRC) and Niger have become flashpoints in the exercise of the respective roles entrusted to the African Union(AU) Peace and Security Council and Regional Economic Communities/Regional Mechanisms (RECs/RMs) for peace and security in their respective legal and policy instruments. While subsidiarity is the principle most invoked as the formula for governing the relationship between the PSC and RECs/RMs, not only what subsidiarity entails in terms of who does what and when remains unclear and contested leading to confusion and even policy paralysis in dealing with specific conflict situations but also such overuse of the term has obscured the fact that it is one among many principles and frameworks for governing the relationship between the AU and RECs/RMs.