Rationale for freedom of expression based on an analogy of communication to goods in the economic marketplace. The theory holds that the truth arises out of the competition of ideas in an open market. Freedom of speech is the right to freely say what one pleases, as well as the related right to hear what others have stated. ...

The rationale is articulated in U.S. Supreme Court case law in the case Abrams v. U.S. 250 US 616, 1919. The dissenting opinion here written by Justice Oliver Wendell Holmes and joined by Justice Louis Brandeis is, according to the U.S. State Department, "widely recognized as the starting point in modern judicial concern for free expression." (Source) Holmes explains in this famous dissent: "Persecution for the expression of opinions seems to me perfectly logical. If you have no doubt of your premises or your power and want a certain result with all your heart you naturally express your wishes in law and sweep away all opposition.... But when men have realized that time has upset many fighting faiths, they may come to believe even more than they believe the very foundations of their own conduct that the ultimate good desired is better reached by free trade in ideas -- that the best test of truth is the power of the thought to get itself accepted in the competition of the market, and that truth is the only ground upon which their wishes safely can be carried out. That at any rate is the theory of our Constitution." The Supreme Court Building, Washington, D.C. The Supreme Court Building, Washington, D.C., (large image) The Supreme Court of the United States, located in Washington, D.C., is the highest court (see supreme court) in the United States; that is, it has ultimate judicial authority within the United States... 1919 was a common year starting on Wednesday (see link for calendar). ... Oliver Wendell Holmes Jr. ... Louis D. Brandeis Louis Dembitz Brandeis (November 13, 1856 - October 3, 1941) was an important American litigator, Justice, advocate of privacy, and developer of the Brandeis Brief. ... The United States Department of State, often referred to as the State Department, is the Cabinet-level foreign affairs agency of the United States government, equivalent to foreign ministries in other countries. ...

The marketplace of ideas is also a theory that claims that we ought to be exposed to a wide array of ideas and thoughts in order to be able to pick the idea that best suits us. If the marketplace of ideas is limited, humans can not make well informed decisions and communities (state, national and/or global) are directly impacted.