The script is not bad, the directing and all not bad either ... but although Dylan McDermott was brilliant--if not perfect--in playing his character in every setting in The Practice, Lt Carter Shaw in Dark Blue is one role which should never have been offered to him/which he should never have accepted.
Let us face it, nearly every actor/actress has roles they cannot possibly play convincingly--Streep can pull off Sophie's Choice, The Devil Wears Prada and Mamma Mia, but that does not mean that everyone else can.
If you adore Dylan McDermott even if he just sat there watching paint dry, then there is no reason for you not to enjoy Dark Blue. But if you are the type of viewer who is distracted by actors playing roles which do not suit them--as in Michael Weston in BURN NOTICE Season 3-Episode 5 "Signals and Codes"--then you will be distracted throughout much of Dark Blue.