Colorado Revised Statutes Title 18. Criminal Code § 18-1-503.5. Principles of criminal culpability

(1) If the criminality of conduct depends on a child being younger than eighteen years of age and the child was in fact at least fifteen years of age, it shall be an affirmative defense that the defendant reasonably believed the child to be eighteen years of age or older. This affirmative defense shall not be available if the criminality of conduct depends on the defendant being in a position of trust.

(2) If the criminality of conduct depends on a child's being younger than eighteen years of age and the child was in fact younger than fifteen years of age, there shall be no defense that the defendant reasonably believed the child was eighteen years of age or older.

(3) If the criminality of conduct depends on a child being younger than fifteen years of age, it shall be no defense that the defendant did not know the child's age or that the defendant reasonably believed the child to be fifteen years of age or older.