I explore the medieval phenomenon of the Hanseatic League. I use the concept of functional overlapping competing jurisdictions (FOCJ) discussed by Frey and Eichenberger (1996, 1999, 2000) as framework for my analysis of the medieval association of northern European traders and cities. I show that the Hanseatic League came close to representing an example of a FOCJ. But I find that in contrast to the FOCJ outlined by Frey and Eichenberger the polycentric Hanseatic League as an inter-regional structure lacked the characteristic of a jurisdiction. It was not a political authority with the power to tax and regulate its members. The arrangements between the members of the Hanseatic League therefore had to be self-enforcing. Building on my investigation of the Hanseatic League, I further provide a general discussion of the costs and benefits of a central political authority in a system of functional overlapping competing units.