18-12-106. Prohibited use of weapons.
(d) The person has in his or her possession a firearm while the person is under the influence of intoxicating liquor or of a controlled substance, as defined in section 12-22-303, C.R.S. Possession of a permit issued under section 18-12-105.1, as it existed prior to its repeal, or possession of a permit or a temporary emergency permit issued pursuant to part 2 of this article is no defense to a violation of this subsection.
Most people assume it's the same as the limit for driving but it's unclear. This lack of a definition was brought up in People v. Beckett but the court ruled the lack of a definition did not matter because the individual testified that he was too drunk to drive.