Focusing on the history, mechanisms and application of State immunity in international litigation, this talk provided an in-depth and informative review of this well-established principle in international law. The speaker, Mr Adrian Lai, Deputy Secretary General of the Academy, started with a brief introduction of the legal basis of State immunity, par in parem non habet imperium, meaning equals have no authority over one another, and proceeded to consider its application in the earliest cases as well as the legal arguments revolving around the issues of access to justice, respect of sovereignty, and the enforcement proceedings. Mr Lai further discussed key incidents that propelled the shift from absolute immunity to restrictive immunity and specifically explored immunity in commercial transactions, especially in cases where State-owned enterprises were concerned, touching upon the 2004 Draft Convention, the UK State Immunity Act, and the US Foreign Sovereign Immunities Act.