The refusal of the U.S. Supreme Court to hear an appeal of a ruling that South Dakota's ban on corporate farms is illegal casts doubt about a similar ban in Nebraska.
An earlier appeals court ruling found South Dakota's Amendment E unconstitutional because it interferes with interstate commerce.
The high court declined, without comment, Monday to review the ruling.
The 1998 amendment was designed to protect the state's farmers from unfair competition from big corporations.
It generally excludes non-family farm corporations from owning farmland or farming in South Dakota.
Nine Midwestern states have similar laws on the books.
Nebraska's ban, widely known as Initiative 300, was approved by voters in 1982.
Keith Olson, president of the Nebraska Farm Bureau, said the high court's decision, "certainly casts a shadow on Nebraska's similar law."