比賽的勝負可能會因為裁判的誤判而導致勝敗得失的轉變，球員或運動員個人在運動場上的成就，也有可能因為裁判的判決而消失。為了比賽的公平性與公正性，輔助裁判判決的即時重播系統的應用，恰好可以彌補這方面的不足，減少球場上的爭議。本文首先就即時重播系統的發展及影響加以簡介，接著針對最早運用此一系統職業運動：美式職業足球聯盟及美國職棒大聯盟及世界少棒聯盟為例，對其運用規則及範圍加以介紹，供國內相關賽事在未來導入即時重播系統時的參考。

The wrong call of umpires or referees of the game might cause the team from winning the game to lose. Moreover, player's achievement might disappear because of the wrong call. Therefore, the adaption of instant replay system of sport organizations would help the umpires or referees to make the right call, and in order to improve the fairness and justice of the game. This study introduced the scope and rules of National Football League (NFL), Major League Baseball (MLB) and Little League Baseball (LLB) that have adapted instant replay system. These materials could be a helpful reference for the sport organizations as they make to use of this system.