Which case is known for declaring that money is a form of protected speech under the First Amendment?

The case known for declaring that money is a form of protected speech under the First Amendment is Citizens United v. FEC. This landmark Supreme Court decision held that the government cannot restrict independent expenditures in political campaigns, as it would violate the principle of free speech. The Court determined that spending money to influence elections is a form of protected speech, thereby allowing corporations and unions to spend unlimited amounts of money on political advocacy.

This ruling emphasizes the idea that the First Amendment protects not just spoken or written words, but also financial contributions that support political expression. In practical terms, this decision significantly changed the landscape of campaign financing, facilitating an increase in the role of money in politics. Understanding this case is vital for grasping the intersection of finance, politics, and constitutional rights in the United States.