.In 1994 the Board of County Commissioners of Yellowstone County, Montana, created Zoning District 17 in a rural area of the county and a planning and zoning commission for the district. The commission adopted a zoning regulation, which provided, among other things, that "dwelling units" could be built only through "on-site" construction. Later county officials were unable to identify any health or safety concerns that were addressed by requiring on-site construction There was no evidence that homes built off-site (prefabricated in a factory) would negatively affect property values or cause harm to any other general welfare interest of the community. In December 1999 Francis and Anita Smith bought two, forty-acre tracts in District 17. The Smiths bought a modular home and moved it onto the property the following spring. Within days the county advised the Smiths that the home violated the on-site construction regulation and would have to be removed. The Smiths filed a suit in a Montana state court against the county.

Assume you are their lawyer. What constitutional argument would you present, and explain what standard the court would apply to determent whether the regulation is constitutional.