Final answer:
The 1948 Antitrust Paramount Decision was a landmark Supreme Court case that ended monopolistic practices in the film industry, such as studios owning their own theaters and block booking, under U.S. antitrust laws.
Step-by-step explanation:
The 1948 Antitrust Paramount Decision, known formally as the Supreme Court case United States v. Paramount Pictures, Inc., was a major event in the history of U.S. antitrust law enforcement. This landmark decision reached by the U.S. Supreme Court held that the existing distribution scheme of film studios owning their own theaters and holding exclusivity rights on which theaters would show their films constituted a practice of anti-competitive, monopolistic behavior. It effectively ended the old Hollywood studio system by making it illegal for film studios to own their own theaters and by banning certain anti-competitive practices such as block booking (in which studios forced theaters to book a block of films together) and price fixing.
This decision was an enforcement of antitrust laws, particularly following the Sherman Antitrust Act of 1890, which aimed to maintain competition within various industries and prevent monopolies. By forcing the separation of film production and exhibition companies, the ruling caused the film industry to restructure and promoted a more competitive market, allowing for more varied and independent film distribution.