Colo. Rev. Stat. § 31-25-1101
This part 11 is intended to provide a summary method for the collection of delinquent assessments and shall be liberally construed in favor of the taxing authority and the grantee in any deed issued pursuant to its provisions. No collateral attack whatsoever shall be permitted by any court or tribunal upon the title thus acquired, whether said title is acquired by the taxing authority itself or by any other purchaser. All taxing authorities within the state of Colorado authorized to levy any special tax or assessment are hereby specifically authorized to take advantage of the provisions of this part 11 and to take, hold, and convey title to the property sold. Conveyances shall be authorized by order of the governing body of the taxing authority, without any other further formality or proceeding.
C.R.S. § 31-25-1101