Colo. Const. art. IX, § 8

Religious test and race discrimination forbidden - sectarian tenets. No religious test or qualification shall ever be required of any person as a condition of admission into any public educational institution of the state, either as a teacher or student; and no teacher or student of any such institution shall ever be required to attend or participate in any religious service whatsoever. No sectarian tenets or doctrines shall ever be taught in the public school, nor shall any distinction or classification of pupils be made on account of race or color, nor shall any pupil be assigned or transported to any public educational institution for the purpose of achieving racial balance.