The U.S. Supreme Court case American Tradition Partnership, Inc., FKA Western Tradition Partnership, Inc., et al. v. Steve Bullock, Attorney General of Montana, et al., 2011 was a significant ruling that reaffirmed the court's previous decision in Citizens United v. Federal Election Commission (2010). The plaintiffs challenged a Montana state law that banned corporations from making independent political expenditures - arguing it violated their First Amendment rights to free speech as established by Citizens United precedent which allowed corporations and unions to spend unlimited amounts on political campaigns independently of individual candidates or parties. The Supreme Court ruled summarily in favor of the plaintiffs without oral argument or written opinion beyond stating that there was no valid reason to distinguish this case from its earlier ruling in Citizens United; thus striking down the century-old Montana law and further solidifying corporate campaign spending protections under the First Amendment.

In the dissenting opinion for American Tradition Partnership, Inc., et al. v. Steve Bullock, Attorney General of Montana, et al., Justice Breyer argued that the court's decision to strike down a century-old Montana law limiting corporate spending in elections was incorrect and inconsistent with previous rulings on campaign finance reform. He contended that the majority failed to consider evidence presented by Montana demonstrating how unrestricted corporate money could lead to corruption or its appearance - a key factor in upholding such restrictions under past Supreme Court precedent. The justice also criticized the majority for summarily reversing without full briefing or argument, suggesting this case raised important questions about applying Citizens United principles at state level which deserved more thorough consideration.