This essay sets out to compare democratic legitimacy in three federal systems: United States of America (USA), European Union (EU) and Germany. The main question of the essay concerns the institutional design of the USA, EU and Germany's federal systems and how it is likely to affect democratic legitimacy. This main question is divided into four subqueries that lead the empirical analysis. These are: 1) What does the federal system's electoral process look like?, 2) How many voters do the federal systems have per mandate?, 3) In what ways do laws, rules and decisions create restrictions on the democratic process of the different systems?, and 4) Are there any changes and trends in development that may lead to weaker / stronger democratic legitimacy in the three federal systems? The essay is based on the assumption on legitimacy as a political concept and that it refers to whether people accept the political system's authority. The method for this essay is a comparative study using ‘most similar system design’. The empirical section includes collected material related to democratic legitimacy and the democratic process of the three federal systems, in relation to Robert Dahl's traditional democratic theory demonstrating five criteria a democratic process should achieve. It is difficult to measure to what extent the criteria in the traditional democratic theory are achieved, thus the empirical outcome is not comprehensive. However, it is possible to discuss the outcome and draw conclusions by studying the extent of legitimacy in the systems, in relation to each other. The empirical study thus shows that the German democratic process is more likely to fulfill a democratic process according to Robert Dahl’s democracy theory than the other two systems. USA tend to show more extensive restrictions for fulfilling the requirements of a democratic process than the other two systems. EU:s results is similar to USA, but does not have the same extensive restrictions. Therefore, Germany demonstrates a higher degree of democratic legitimacy than USA and EU do. USA demonstrates a lower degree of democratic legitimacy and EU:s democratic legitimacy is similar to USA. Our hypothesis, that the institutional structure of the system affects the outcome of democratic legitimacy, is thus confirmed in the study results.