BY DAVID KRONKE >TV CRITIC

Television's reigning Iron Man, "Law & Order," returns for its 19th season tonight. Only one other series, "Gunsmoke," lasted longer, and "L&O" stands poised to tie that show for longevity next season.

At this point, Dick Wolf's brainchild can sometimes seem as long in the tooth as "Gunsmoke" got, particularly since it's tied to such a stringent procedural formula. But its writers still manage occasionally to find an intriguing plot twist or issue to tackle to keep viewers hooked.

Alas, that doesn't occur in tonight's episode, which opens with the beating death of a stockbroker in broad daylight, which unveils a citywide "Fight Club"-style underground. And, thanks to the clumsy handling of the case, forces District Attorney Jack McCoy (Sam Waterston) - who needs to project a tough-on-crime front during his campaign for re-election - to pursue a dubious legal channel to serve justice.

Several early episodes of the new season find McCoy's underling, the rigidly ethical prosecutor Matthew Cutter (Linus Roache), bristling at his boss's edicts. Future episodes have Cutter grappling with a judge (guest star Ned Beatty) with diminishing faculties and a fundamentalist offshoot of the Mormon religion that practices polygamy ("Law & Order: Big Love"?). The courtroom drama tends to diminish the cop stuff, consigning detectives Lupo (Jeremy Sisto) and Bernard (Anthony Anderson) largely to the sidelines.

There's also a regrettably manipulative episode involving mentally disabled witnesses that may inadvertently remind you of Ben Stiller's turn as "Simple Jack" in the summer hit comedy "Tropic Thunder." So "Law & Order" is hit-and-miss (the dialogue, in particular, tends toward the ripe), but for a show nearly two decades old, it's pretty impressive that this procedural vehicle isn't completely running on fumes.

Meanwhile, fans of "Law & Order: Criminal Intent" and Jeff Goldblum will have to wait.

USA Network has pushed back the start date of the eighth season of "Law & Order: Criminal Intent" to the first quarter of 2009 from its original bow on Friday.

This will allow the new season to run uninterrupted for 16 episodes. No other reason was given for the postponement.

Oscar nominee Goldblum joins the established cast as Detective Zach Nichols, stepping into the vacancy left by the departure of Chris Noth, who played Detective Mike Logan. "L&O: CI" also boasts the talents of Vincent D'Onofrio as Detective Robert Goren, Kathryn Erbe as Detective Alexandra Eames, Julianne Nicholson as Detective Megan Wheeler and Eric Bogosian as Capt. Danny Ross.

USA originally provided an episode for Friday but not one featuring Goldblum, just a couple of clips of him doing his trademark stammering/pausing/speaking. Goldblum is a reliably entertaining actor; here's hoping the writers give him more to work with than they did series veteran D'Onofrio in the episode they sent.

David Kronke, (818) 713-3638 david.kronke@dailynews.com

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LAW & ORDER

>What: 19th-season premiere of the venerable crime procedural.

>Where: NBC (Channel 4).

>When: 10 pm Wed.

>In a nutshell: Future episodes are stronger than tonight's.