Colo. Rev. Stat. § 42-1-228
In any administrative proceeding for a revocation of a driver's license pursuant to article 2 of this title, where the hearing officer is engaged in finding facts and applying law for an incident or offense reported directly to the department by a law enforcement officer, and where the revocation was not triggered in whole or in part by a record of a conviction, the driver may challenge the validity of the law enforcement officer's initial contact with the driver and subsequent arrest of the driver. If a driver so challenges the validity of the law enforcement officer's initial contact, and the evidence does not establish that the initial contact or arrest was constitutionally and statutorily valid, the driver is not subject to license revocation.
C.R.S. § 42-1-228