Africa’s regional economic communities (RECs) are increasingly active forums for both economic and political issues in the continent. After several political coups in Mali, the Economic Community of West African States (ECOWAS) imposed wide-ranging economic and political sanctions on Mali, in the context of ECOWAS’s mandate regarding democracy and good governance. These sanctions were then mirrored by the West African Economic and Monetary Union (WAEMU). The WAEMU sanctions led Mali to bring a case before the WAEMU Court of Justice, resulting in a rare instance of judicial review, by a regional court, of acts taken by a REC. This article examines the landmark decision rendered by the WAEMU Court of Justice in 2022, in the case Mali v. The Conference of Heads of State and Government of the WAEMU, by which the Court’s President ordered the suspension of the execution of the WAEMU sanctions. We analyse the WAEMU’s constituent instruments, examine the interactions between the overlapping mandates of the WAEMU and ECOWAS, and consider their potential impact on the validity of the sanctioning decision. We argue that the decision taken at the Union’s level is difficult to justify under the applicable international law.