The Minnesota Chamber of Commerce asked a federal judge Thursday to declare unconstitutional parts of a state law that prohibits corporations from making independent expenditures on behalf of political candidates, citing a U.S. Supreme Court ruling that struck down a similar federal law.

Chamber attorney Thomas Boyd also asked U.S. District Judge Paul Magnuson to bar all Minnesota prosecutors from enforcing those provisions. He said the law chills the business advocacy group and its members from exercising their free speech rights out of fear of penalties.