Why is the term "illegal per se" significant in antitrust cases?

The term "illegal per se" is significant in antitrust cases because it indicates that certain actions or agreements are deemed inherently unlawful, regardless of their effects or the context in which they occur. This means that, once a practice is categorized as illegal per se, it does not require the courts to investigate or prove any negative impact on competition or consumers. The mere existence of the practice suffices for it to be considered illegal under antitrust laws. This automatic determination simplifies legal proceedings because it bypasses the often complex and lengthy analysis of whether a practice causes harm to competition, thereby providing a clear and straightforward approach to enforcing antitrust regulations.