Mont. Code Ann. § 81-23-201

In a market where the provisions of this chapter apply, it is unlawful for a producer, producer-distributor, distributor, or jobber to produce, transport, process, store, handle, distribute, buy, or sell milk unless the dealer is properly licensed as provided by this chapter. It is unlawful for a person to buy, sell, handle, process, or distribute milk that the person knows or has reason to believe has been previously dealt with or handled in violation of any provision of this chapter. The board may decline to grant a license or may suspend or revoke a license already granted upon due cause and after hearings.