This Article encompasses a three level analysis of the content-of-laws enquiry in International Arbitration. Firstly, it explores the theoretical underpinnings and the various approaches articulated in legal theory to the establishment of the content of the applicable law in international litigation and arbitration. Secondly, on the basis of an elaborate comparative review of the various legal regimes and jurisprudence in the most frequently selected venues of arbitration, namely England & Wales, France, Hong Kong, Singapore, Switzerland, the State of New York (USA), and Sweden, as well as in leading investment arbitration fora, it challenges conventional wisdom by showcasing the emerging trend toward the application of a “facultative” jura novit arbiter principle in international arbitral proceedings. Thirdly, it delineates a clear modus operandi for arbitral tribunals and national courts reviewing arbitral awards in annulment proceedings and offers model clauses, arbitration rules, and national law provisions on the content-of-laws enquiry. Finally, it concludes with remarks and observations that amplify the importance of continuous governing law related consultations between the parties and the arbitrators throughout the arbitral proceedings and, certainly, before the tribunal has rendered its final award.