Colo. Const. art. V, § 22

Reading and passage of bills. Every bill shall be read by title when introduced, and at length on two different days in each house; provided, however, any reading at length may be dispensed with upon unanimous consent of the members present. All substantial amendments made thereto shall be printed for the use of the members before the final vote is taken on the bill, and no bill shall become a law except by a vote of the majority of all members elected to each house taken on two separate days in each house, nor unless upon its final passage the vote be taken by ayes and noes and the names of those voting be entered on the journal.