California farm groups have stepped into a U.S. Supreme Court battle over a state law allowing unions to enter agricultural property.

brief filed recently argues the state is ignoring a Fifth Amendment right for private property owners to exclude third parties. “California has upended that proposition for the sake of one privileged group: organized labor,” the groups claim. They add that regulations, passed by the Agricultural Labor Relations Board, “coerce acceptance of physical invasion.”

The brief includes the California Fresh Fruit Association, the Grower Shipper Association of Santa Barbara and San Luis Obispo Counties, the Ventura County Agricultural Association and Western Growers.