Antitrust laws - also referred to as "competition laws" - are statutes developed by the U.S. Government to protect consumers from predatory business practices by ensuring that fair competition exists in an open-market economy. Antitrust laws are applied to a wide range of questionable business activities, including but not limited to:
- Market Allocation:
Suppose my company operates in the Northeast and your company does business in the Southwest. If you agree to stay out of my territory, I won't enter yours, and because the costs of doing business are so high that startups have no chance of competing, we both have a de facto monopoly.
- Bid Rigging: There are three companies in an industry, and all three decide to quietly operate as a cartel. Company 1 will win the current auction, so long as it allows Company 2 to win the next and Company 3 to win thereafter. Each company plays this game so that all retain current market share and price, thereby preventing competition.
- Price Fixing: My company and your company are the only two companies in our industry, and our products are so similar that the consumer is indifferent between the two except for price. In order to avoid a price war, we sell our products at the same price to maintain margin, resulting in higher costs than the consumer would otherwise pay.
At the core, antitrust provisions are designed to maximize consumer welfare. (For more on this read, Antitrust Defined.)
This question was answered by Justin Bynum.