In the case of United States and Department of Agriculture v. United Foods, Inc., 2000, the Supreme Court ruled that mandatory assessments imposed on mushroom growers by the Mushroom Promotion, Research and Consumer Information Act to fund generic advertising violated their First Amendment rights. The court held in a 6-3 decision that such compelled subsidies for speech were not part of any broader regulatory scheme which could justify them as necessary incidents. Unlike previous cases where similar schemes had been upheld because they were tied to more comprehensive regulation or because they concerned agricultural products with regulated marketing orders, this was not true for mushrooms. Therefore forcing producers like United Foods to pay for advertisements they disagreed with constituted an unconstitutional infringement on their freedom of speech.

In the dissenting opinion for United States and Department of Agriculture v. United Foods, Inc., Justice Breyer argued that the majority's decision to strike down a government program requiring mushroom producers to contribute funds towards generic advertising was incorrect. He contended that this kind of economic regulation is commonplace in American law and does not violate any First Amendment rights as it doesn't force anyone to endorse or finance political or ideological views they disagree with. Instead, he viewed it as an example of collective action designed to help an industry overcome a common problem - free-riding by companies who benefit from such advertising without contributing financially. He also pointed out that if all similar programs were invalidated on these grounds, many other industries would be affected negatively.