Montanans Against Irresponsible Densification, LLC v. State of Montana

In 2023, the Montana legislature (defendant) adopted four laws intended to address the state’s housing shortages and to make affordable housing available for Montana citizens of all income levels. These laws stated that (1) in some specified conditions, urban areas must allow the construction of multi-unit dwellings; (2) cities with over 5,000 residents must allow duplexes to be built on any lot zoned for single-family homes; (3) cities with over 5,000 residents in counties with over 70,000 residents must update their zoning laws within five years to address anticipated housing needs over the next 20 years; and (4) all municipalities must allow the construction of separate, smaller accessory dwelling units (ADUs) on any property zoned for single-family homes. Montanans Against Irresponsible Densification, LLC (MAID) (plaintiff) filed a lawsuit challenging the constitutionality of all four laws, arguing that they violated equal-protection principles, violated substantive-due-process principles, unlawfully preempted local zoning laws, and unlawfully limited public participation in the zoning process. For the equal-protection claim, MAID pointed out that laws did not apply to homeowners who were subject to private restrictive covenants (e.g., homeowners’-association agreements) but did apply to homeowners governed only by zoning laws. For the substantive-due-process claim, MAID claimed the four laws were arbitrary because they were not uniform. Rather, each law used different city sizes as requirements and defined the same terms (e.g., duplex) differently. For the public-participation claim, MAID pointed out that the law requiring a new 20-year plan did not allow citizen input during all phases of the planning process. After proceedings and appeal about a preliminary injunction, the trial court considered the claims’ merits.