Final answer:
Antitrust law is legislation intended to control monopoly power and promote competition in the market, making practices like price-fixing, collusion, and rigging bids illegal in the United States.
Step-by-step explanation:
Antitrust law is a significant aspect of both law and economics, focusing on promoting fair competition and prohibiting monopolistic behaviors. The purpose of antitrust legislation is to control monopoly power and preserve as well as promote a healthy competitive market.
In the United States, various anticompetitive practices are illegal under antitrust laws. These include but are not limited to, agreeing to fix prices or output, collusion between firms (e.g., forming a cartel), bid rigging, and dividing markets by pre-arranging the allocation of customers, suppliers, territories, or lines of commerce.
The enforcement of these laws falls to entities such as the Federal Trade Commission and the U.S. Department of Justice. Antitrust laws not only block mergers that could reduce competition but also prohibit restrictive practices that, while not outright price or quantity fixing, could dampen competitive forces. There's a historical context to this legislation: critics in the past have argued that without competition, dominant firms might become less efficient and innovative, ultimately harming consumers by raising prices and enjoying persistently high profits.