In practice, it is not only important to acquire in-depth knowledge about tax law and to seek for the most convincing legal arguments. It is also important to convince clients, tax administrations, courts or readers of those arguments by writing clearly, concisely and in a structured manner. Thus, the lecture aims to provide a better understanding of how to structure legal arguments and draft legal opinions. The course will begin with questions and discussions about different issues regarding legal opinions, such as the differences between legal opinions and academic papers, the expectations of the potential audiences, and the different styles of structure and writing. Afterwards, practical case studies in tax treaty law will be analyzed by teams of students, who will then write legal opinions from different perspectives (taxpayer, tax administration, court). By sharing and discussing the different experiences in class, the lecture intends to develop an understanding of how your writing skills may turn a good legal opinion into a great legal opinion.