What must a plaintiff demonstrate to achieve a favorable ruling in a federal antitrust lawsuit?

In a federal antitrust lawsuit, the plaintiff must demonstrate evidence of harm to competition to achieve a favorable ruling. This means that the plaintiff needs to show that the conduct in question has had an adverse effect on the competitive landscape of the market. The focus is on whether the actions of the defendant have significantly restrained trade or commerce, reduced market competition, or caused damage to consumers or other businesses.

Harm to competition can be established through various forms of evidence, such as market analysis, expert testimony, and documentation showing how the behavior of the defendant has impacted other competitors or consumers in the market. Without proving harm to competition, there is typically no basis for an antitrust claim, as the law is designed to protect the competitive process rather than individual business interests alone.

The other options involve requirements that are not necessary for a plaintiff to prevail in an antitrust case. For instance, a written agreement may be relevant in certain cases, especially in proving collusion, but it is not a blanket requirement for all antitrust claims. Similarly, while proving the existence of a monopoly can be important in some cases, it is not a necessity for demonstrating harm to competition. Lastly, the requirement that the plaintiff's business operates at a state level is not relevant,