The Constitutio Romana (or “Roman Constitution”) was drawn up between King Lothair I of Italy (818–855), co-emperor with his father, Louis the Pious, since 817, and Pope Eugene II (824–827) and confirmed on 11 November 824.
Eugene agreed to several concessions to imperial power in central Italy in return for receiving the military and juridical support of Lothair.
It also restored the custom established by Pope Stephen III in 769 whereby both the laity and clergy of Rome would participate in Papal elections.
There has been some debate between modern scholars whether the Constitutio was a "dead letter" with little practical impact, or marked a stage of the road to imperial domination of the Papacy.
[2] The constitution advanced the imperial pretensions in the city of Rome, but also established a system to check the power of the nobles.