Under federal law (applicable in all states) it is illegal for a person to knowingly or intentionally possess a controlled substance, unless the substance was obtained through a valid prescription or order from a practitioner, while acting in the course of the practitioner’s professional practice. See 21 U.S.C. §844.

The term controlled substance means a drug or other substance—or an immediate precursor to the drug or other substance—that is included in schedule I, II, III, IV, or V of the relevant portion of the United States Code (statute). See 21 U.S.C. §841.

The term practitioner means a physician, dentist, veterinarian, scientific investigator, pharmacy, hospital, or other person licensed, registered, or otherwise permitted by the United States or the jurisdiction (state) in which he practices or does research to distribute, dispense, conduct related research, administer, or use in teaching or chemical analysis a controlled substance in the course of such professional practice or research. 21 U.S.C. §802(21).

As under federal law, state laws usually classify substances in groups or schedules that determine which substances are included in the definition of controlled substances, and the potential penalties or punishments for possessing them without legal authorization. Criminal charges and penalties for these offenses vary from state to state and are usually located in a state’s statutes—often in the penal or criminal code. Illegal possession of controlled substances may also be prosecuted under federal law. See 21 U.S.C. §844.

Under both federal and Colorado state law, it is illegal to possess a controlled substance without a valid prescription or order from a licensed practitioner. Controlled substances are classified into schedules I through V according to their potential for abuse, medical use, and safety, as outlined in 21 U.S.C. §841. Practitioners, as defined in 21 U.S.C. §802(21), include professionals like physicians and pharmacists who are authorized to handle controlled substances within the scope of their practice. In Colorado, the state's statutes align with federal regulations and categorize drugs into schedules. The penalties for illegal possession of controlled substances in Colorado can vary based on the type and amount of the substance, and whether the offense is prosecuted at the state or federal level. The specific statutes detailing these regulations and penalties can be found in the Colorado Revised Statutes, particularly under the Uniform Controlled Substances Act of Colorado.