Abstract: This paper does three things: (1) Based on a limited number of theoretically established dimensions, it proposes a new indicator for the rule of law. (2) This indicator is used to shed new light on the relationship between the rule of law and the political system of a country. Six clusters with typical combinations of levels of the rule of law and levels of democracy are identified. Presidential governments tend to score significantly worse on the rule of law indicator than parliamentary ones. Many presidential democracies are even outperformed by dictatorships. (3) The paper finally inquires into the roots of the rule of law. It turns out that a number of causes of long-term development are also linked to the rule of law. Particularly geographic factors and the share of European descendants in today’s population are significantly correlated with the rule of law.