This study presents the main features of patent law in the European Union, the United States and China, with a special focus on patentability. Each patent regime is reviewed in its historical context, exploring the stages leading to the given jurisdiction's contemporary patent law. After mapping the differences and similarities of patent law in the EU, the US and China, possible reasons for the detected divergence and convergence will be explored. This study reveals that the differences in codified patent law between the EU, the US, and China are for the most part a matter of nuance and much of the convergence stems from international harmonization efforts and common historical roots as well as external pressure to convergence in patent law for mainly economic reasons. Whereas patent laws in the EU and US are more established, China's patent law has been moulded into its contemporary form only recently. Differences across the chosen jurisdictions are explained not only by cultural factors but also by underlying theoretical differences in patent doctrine and differing aims of patent protection, as well as the divide concerning the role of statutory law and case law between the common law and Romano-Germanic law.