The Shield breaks the conventional formula of the cop genre. It plays out in a tough, morally ambiguous world in which the line between good and bad is crossed ever day. The series focuses on the tension between a group of corrupt but effective cops and a captain torn between bringing them down and advancing his own political ambitions. The Shield stars Michael Chiklis (The Commish) as rogue cop "Det. Vic Mackey," leader of the elite Strike Team unit, who is effective at eliminating crime but who operates under his own set of rules. Benito Martinez (Outbreak & Her Costly Affair) plays "Captain David Aceveda," the young precinct head who doesn't like Mackey's tactics and wants to bust him off the force. And the Emmy-nominated CCH Pounder (ER & Boycott), plays "Det. Claudette Wyms," a veteran detective who understands Mackey and knows how to play both sides of the fence.

The show made history by becoming the first ad-supported cable series to win the 2003 Golden Globe Award for Best Drama Series. In its first season, Shawn Ryan (Writing) and Clark Johnson (Directing) received Emmy nominations, which were also firsts for basic cable in those categories. The Shield has received two TCA nominations for Outstanding Achievement in Drama. As of March 2005, the show has become the longest running series on the FX Network.