Anyone who digs The Shield & The Wire should check Homicide: Life on the Street. Incredible series that was loosely based on David Simon's (The Wire) first book and still considered as one of the best shows network TV has ever done. First 2 shorter seasons are good but they're still finding their ground tonally, and the 7th season is lacking but 3-5 are probably the best 3 seasons that network TV drama has done. There's also a movie after season 7 that concludes the whole series.
Plus Homicide is basically the backbone for why TV drama is so good now overall. (Homicide's success & production team's frustration with networks led to the writers, producers & crew to create Oz on HBO. Oz was the first of the HBO dramas and that success established HBO as a drama powerhouse, making Deadwood, Wire, Sopranos, etc... HBO's success led to FX wanting to copy that model w/ original programming with The Shield. The Shield's & FX's overall success led to the boom of original drama on basic cable & pay cable.)