The Constitution of the Kingdom of Westphalia was the oldest constitution in Germany, adopted by the Kingdom of Westphalia on November 15, 1807. It was drafted based on the French Constitution of 1804 and served as a model for the constitutions of other states in the Confederation of the Rhine, the Napoleonic union of German states (e.g. the Grand Duchy of Frankfurt). The Constitution was adopted by royal decree on December 7, 1807 and published in the law bulletin.