Mandate Migration of UNSC? Middle-Power Brokerage and the Redistribution of Authority in International Law

The transition toward a multipolar order has intensified rivalry among the permanentmembers of the United Nations Security Council (UNSC). US-China competition is central,but Russia-West confrontation and US support for Israel also explain why the Councilbecomes paralysed in politically salient conflicts. This paper examines the resulting shift fromUN-centred collective security to middle-power brokerage. It compares UNSC practiceconcerning Syria, Ukraine and Palestine/Israel with mediation by Qatar, Turkiye, SaudiArabia and Pakistan in Gaza, the Russia-Ukraine war and the 2026 US-Iran war. Throughprocess tracing, structured comparison and doctrinal legal analysis, the paper distinguishesdiplomatic effectiveness from legal authority. It argues that middle-powers increasinglyexercise "process authority": they convene adversaries, frame bargains and supportimplementation when the Council is blocked. They do not, however, inherit the Council'sCharter authority. The emerging order is one of brokered legal pluralism - more responsiveand sometimes life-saving, but also more opaque, selective and dependent on state leverage.The analysis shows that middle-power diplomacy strengthens international law when itoperationalizes existing obligations and remains institutionally embedded; it weakens lawwhen political compromise obscures legal asymmetry, substitutes soft commitments forbinding rules, or enables forum shopping.