They began by limiting the authority of the Doge, who, though elected for life, was in 1032 forbidden to associate his son in the supreme office of the state.

In 1172 the election of the Doge was transferred from the people to the Grand Council, who, as a co-opting body, tended to become a close aristocracy.

In 1179 the Ducal power was still further restricted by the creation of a senate called the Quarantia for the administration of justice; while in 1229 the Senate of the Pregadi, interposed between the Doge and the Grand Council, became an integral part of the constitution.
To this latter Senate were assigned all deliberations upon peace and war, the voting of supplies, the confirmation of laws.

Both the Quarantia and the Pregadi were elected by the Consiglio Grande, which by this time had become the virtual sovereign of the State of Venice.

It is not necessary here to mention the further checks imposed upon the power of the Doges by the institution of officials named Correttori and Inquisitori, whose special business it was to see that the coronation oaths were duly observed, or by the regulations which prevented the supreme magistrate from taking any important action except in concert with carefully selected colleagues.