A more thorough explanation:

A restraint of trade is any action or agreement that limits a person or company's ability to participate in business transactions. This term is often used in the context of government regulations that aim to prevent anti-competitive behavior.

For example, in the United States, federal law prohibits any contract, combination, or conspiracy that restrains trade or commerce between states or with foreign nations. This means that companies cannot engage in activities that limit competition, such as price-fixing or monopolizing a market.

One example of a restraint of trade is the case of American Needle, Inc. v. National Football League. In this case, the Supreme Court found that the NFL's licensing activities, which were conducted through a separate corporation, could be considered a restraint of trade. This is because the licensing activities could limit competition among individual teams and prevent other companies from entering the market.

Many states also have their own laws that prohibit restraints of trade. For instance, Massachusetts law states that any contract, combination, or conspiracy that restrains trade or commerce within the state is unlawful.

Overall, restraints of trade are actions or agreements that limit competition and can harm consumers by reducing choices and increasing prices. Governments regulate these activities to promote fair competition and protect consumers.