Mo. Rev. Stat. § 479.270

If transferred by the supreme court or if assigned by the presiding judge of the circuit or pursuant to court rule, a circuit judge may hear municipal ordinance violation cases in those instances where provision is made in this chapter for such cases to be initially heard by an associate circuit judge and may exercise the other powers granted associate circuit judges by this chapter. Costs shall be assessed in the same amounts as if the cause was heard by an associate circuit judge. Such transfer or assignment may be on a case-by-case or general basis.