Mont. Code Ann. § 70-33-313
Lot rules
70-33-313 . Lot rules. (1) A landlord may adopt a rule concerning the rental occupancy of a lot and the use of common areas and facilities in accordance with 70-33-311 . A rule may not be unreasonable, and a rule that does not apply uniformly to all tenants of a similar class creates a rebuttable presumption, as defined in 70-33-431 (3), that the rule is unfair.
(2) Each common area facility must be open or available to residents at all reasonable hours, and the hours of a common recreational facility must be posted at the facility.