Colorado constitution
Article XXI
Section 1

A petition signed by registered electors entitled to vote for a successor of the incumbent sought to be recalled, equal in number to twenty-five percent of the entire vote cast at the last preceding election for all candidates for the position which the incumbent sought to be recalled occupies, demanding an election of the successor to the officer named in said petition, shall be filed in the office in which petitions for nominations to office held by the incumbent sought to be recalled are required to be filed; provided, if more than one person is required by law to be elected to fill the office of which the person sought to be recalled is an incumbent, then the said petition shall be signed by registered electors entitled to vote for a successor to the incumbent sought to be recalled equal in number to twenty-five percent of the entire vote cast at the last preceding general election for all candidates for the office, to which the incumbent sought to be recalled was elected as one of the officers thereof, said entire vote being divided by the number of all officers elected to such office, at the last preceding general election; and such petition shall contain a general statement, in not more than two hundred words, of the ground or grounds on which such recall is sought, which statement is intended for the information of the registered electors, and the registered electors shall be the sole and exclusive judges of the legality, reasonableness and sufficiency of such ground or grounds assigned for such recall, and said ground or grounds shall not be open to review.