The count of Barcelona was the ruler of the County of Barcelona and also, by extension and according with the Usages and Catalan constitutions, of the Principality of Catalonia as Princeps for much of Catalan history, from the 9th century until the 18th century. After 1164, with Alfonso II of Aragon and I of Barcelona, the title of count of Barcelona was united with that of king of Aragon, and after the 16th century, with that of king of Spain.

The Catalan constitutions were the laws of the Principality of Catalonia promulgated by the Count of Barcelona and approved by the Catalan Courts. The Corts in Catalan have the same origin as courts in English but instead meaning the legislature. The first constitutions were promulgated by the Corts of 1283. The last ones were promulgated by the Corts of 1705. They had pre-eminence over the other legal rules and could only be revoked by the Catalan Courts themselves. The compilations of the constitutions and other rights of Catalonia followed the Roman tradition of the Codex.