How did the three members of Flanders participate in medieval government?

In the late Middle Ages, the three members of Flanders—comprising the cities of Brugge, Ghent, and Ypres—functioned as a nearly permanent consultation committee that wielded significant political authority.1

Due to the immense size and economic power of these cities, the count of Flanders could not effectively govern without their collaboration. Consequently, the three members held decisive powers over critical state matters, including:

• Legislation and Justice: They exercised authority in shaping the legal and judicial framework of the principality.1
• Taxation and Economic Policy: They played a central role in determining economic policy and managing fiscal matters.1
• International Relations: They exerted strong influence over the principality's foreign affairs.1

During periods of revolt or when the count was absent, the three members automatically assumed the overall exercise of power. This dominance was so absolute that it prevented the spontaneous development of a traditional representative system of three estates (clergy, nobility, and burghers) until the dukes of Burgundy later introduced such assemblies to contain the cities' influence.1