This paper identifies some common errors that occur in comparative law, offers some guidelines to help avoid such errors, and provides a framework for entering into studies of the company laws of three major jurisdictions. The first section illustrates why a conscious approach to comparative company law is useful. Part I discusses some of the problems that can arise in comparative law and offers a few points of caution that can be useful for practical, theoretical and legislative comparative law. Part II discusses some relatively famous examples of comparative analysis gone astray in order to demonstrate the utility of heeding the outlined points of caution. The second section offers a framework for approaching comparative company law. Part III provides an example of using functional definition to demarcate the topic "company law", offering an "effects" test to determine whether a given provision of law should be considered as functionally part of the rules that govern the core characteristics of companies. It does this by presenting the relevant company law statutes and related topical laws of Germany, the United Kingdom and the United States, using Delaware as a proxy for the 50 states. On the basis of this definition, Part IV analyzes the system of legal functions that comprises "company law" in the United States and the European Union. It selects as the predominant factor for consideration the jurisdictions, sub-jurisdictions and rule-making entities that have legislative or rule-making competence in the relevant territorial unit, analyzes the extent of their power, presents the type of law (rules) they enact (issue), and discusses the concrete manner in which the laws and rules of the jurisdictions and sub-jurisdictions can legally interact. Part V looks at the way these jurisdictions do interact on the temporal axis of history, that is, their actual influence on each other, which in the relevant jurisdictions currently takes the form of regulatory competition and legislative harmonization. The method of the approach outlined in this paper borrows much from system theory. The analysis attempts to be detailed without losing track of the overall jurisdictional framework in the countries studied.