National courts, when dealing with cases of immunity, state succession problems, expropriation claims or cross-border environmental claims, often have to resort to customary international law which requires them to identify the normative content of such rules. Customary international law before Austrian courts has been analyzed and established in strikingly contrasting ways over the years: While the in-depth discussion of foreign and domestic judicial practice that the seminal Austrian Supreme Court case of Hoffmann v. Dralle offered in 1950 amounts to an exceptionally diligent analysis in the area of international law, subsequent cases indicate a much more superficial approach: While a few cases have offered at least some light form of analysis with a limited number of foreign court judgments discussed, the vast majority of Austrian jurisprudence dealing with customary international law often merely restates the elements of state practice and opinio iuris, usually by relying on the writings of legal scholars both in the area of international law as well as domestic substantive or procedural law.By presenting a variety of court cases of the past decades, this study focuses on analyzing the different approaches that Austrian courts have taken in identifying rules of customary international law. It will try to give reasons as to why national courts often seem reluctant to engage in a more thorough analysis of custom and why such an approach could be doctrinally dangerous.