JLo, Liotta take the law to a dark place

As many renowned thespians have observed, no matter what you have done before, those who stay in the acting business long enough will inevitably play a television detective.

Even, as it turns out, Jennifer Lopez.

Last seen as hosting “The American Music Awards” and a judge on “American Idol,” Lopez now stars as the morally compromised yet essentially likable Det. Harlee Santos in “Shades of Blue,” NBC’s new police drama that too often hopes narrative complication will pass for psychological complexity.

Created by Adi

Hasak, the series also features Ray Liotta as Harlee’s even more corrupt and compelling boss, Lt. “Woz” Wozniak, as well as a strong ensemble that includes Drea de Matteo (“The Sopranos”) and Vincent Laresca (“Graceland”).

Not that it matters much. The show’s title may be a play on that groundbreaking ensemble drama “Hill Street Blues,” but “Shades of Blue” is first and foremost astar vehicle. Though Liotta does great work and plays the more multifaceted character, all eyes will be on Lopez, who is in virtually every scene.

A tale of devolution rather than transcendence, “Shades” opens with Harlee explaining, via a video on her laptop, how everything went wrong. “I always told myself the end would justify the means. But now that I’m at the end, I can’t justify anything.” She’s obviously a mess and, because she is JLo, much will be made of this.

Also of how good she looks, for a cop, what with those cheekbones and that luminescent skin, in addition to how the show immediately goes out of the way to show us how tough she is by barking orders and taking to the boxing ring within the first few minutes.

This may be true, but so is the fact that the TV screen is littered with pretty- boy detectives and their cheekbones ( aloha, “Hawaii Five- 0,” cheerio, “Sherlock”), so let’s try to resist the beauty angle. Plenty of good- looking men play remarkably good- looking cops, and it often takes a few episodes for them to look natural chasing down tough- talking perps or firing off a few rounds.

In fact, with its insistence on that boxing bout followed by some raunchy sex, “Shades of Blue” dispenses with familiar tropes so quickly and efficiently that it almost seems satiric.

It isn’t, of course. As the first minutes make all too clear, “Shades of Blue” takes itself very seriously: Immediately after Harlee’s teary monologue, we see her expertly “fix” a crime scene to cover for a rookie cop who accidentally kills a drug dealer.

The fact that the dead man isa drug dealer is supposed to mitigate the wrongful shooting for the viewer just as it does for Harlee. A show of the new millennium, this “Blue” comes in shades dark and stained with corruption, more influenced by the twisted morality of “The Shield” than the colorful heroism of Hill Street precinct. Harlee isn’t just criminally loyal to the badge; she’s a cop on the take, part of a team assembled by Woz for this exact purpose.

Woz believes that by providing protection, at a price, to the more reasonable criminal elements, he can control crime in his precinct. No drug dealing near schools, no rough stuff on the streets, no back- talk; Woz runs his precinct with the familial loyalty and constant OCD paranoia of every cinematic mobster.

He is particularly devoted to Harlee and her daughter, Cristina ( Sarah Jeffery), whose bright future — cello lessons! private school! — Harlee will go to any length to ensure.

So when she is caught mid- shakedown by the feds, she has no choice but to turn inform ant—what would become of Cristina should H ar lee goto the slammer?

It all happens remarkably fast, with Hasak obviously hoping that the plot’s twists and turns will distract fromits obvious holes.

FBI Agent Stahl ( Warren Kole) is a predatory creep pretty much from the get-go, which makes it far too easy to root for Harlee and the dirty cops.

Woz is immediately made aware of a mole in his team, which gives Harlee no time to assess her loyalties— she just assumes he will kill her — and makes the FBI look even more cartoonish.

The fact that the mission is compromised before it begins bothers Agent Stahl not at all, making him seem just as corrupt as Woz.

Real moral ambiguity is tougher to maintain than most TV writers seemto realize.

Viewers may be interested in exploring the line between good and bad, but more often than not they are simply looking for characters and/ or a story compelling enough to allow them to overlook the inevitable contradictions and sloppy cheats.

Lopez does a decent enough job — on top of the single- mom angle, Harlee also has a traumatic back story — but it’s Liotta who will make or break “Shades of Blue.”

He’s been in the business for a while now; it’s about time he played a TV cop, good, bad or otherwise.