My thesis is an empirical analysis of State practice of signatories to the Refugee Convention on the principle of non-refoulement post 1951. The thesis cautiously adopts the International Law Commission's (ILC) draft conclusions on the identification and content of customary international law as a benchmark. It then reviews the nature of custom and its formation with a focus on the ILC’s approach. States and scholarly criticisms on the ILC’s approach are considered and a theoretical construct proposed regarding ‘minimum requirements’ required to deem a norm customary. The thesis critically examines Article 36(2) of the Convention and legal scholarships deeming non-refoulement custom against the ‘minimum requirements’ of custom formation benchmark and state practice on non-refoulement. In conclusion, contemporary and empirical insights are proffered to the question on whether non-refoulement is a customary norm and its implications for refugee protection.