Maybe it is possible to clone a classic.

In its 10th season, “Law & Order” has remained a steady if not splashy drama, defying conventional wisdom by surviving numerous cast changes and flourishing.

So NBC finally wised up and ordered a spin-off from that show’s executive producer, Dick Wolf. The result is the richly satisfying “Law & Order: Special Victims Unit,” which debuts at 9 tonight.

“L&O: SVU,” set in the sex-crimes unit, displays what “Law & Order” has exhibited all along: Wolf’s ability to create three-dimensional, flesh-and-blood characters, then find the right actors to play them.

The new series’ lead cop pairing is Elliott Stabler (Chris Meloni, “Oz”) and Olivia Benson (Mariska Hargitay, “ER”). Stabler is the rock of the duo (hence the name), the stoic family man. Benson has a deeply personal stake in pursuing sexual criminals, one that is revealed tonight, and her emotions sometimes get her in hot water.

There are some familiar faces in “SVU.” Captain Donald Cragen (Dann Florek), the first commanding officer in “Law & Order,” returns as the leader of the unit. Richard Belzer reprises his wonderful John Munch character from the late, lamented “Homicide,” as Munch moves to NYC from Baltimore after his wife of one night leaves him for one of his fellow detectives.

As on “Law & Order,” the cases are complex and multilayered. In the opener, a foreign cab driver (is there any other kind in the Big Apple?) is found hacked to death and dismembered. In the end, circumstances turn out to be much more ambiguous than they originally appear, with the victim deserving of death and the killer deserving of mercy.

Unlike many spin-offs, “SVU” is worthy of its parent show. Hopefully, this doesn’t mean “Law & Order” is headed for retirement. But if it is, “Law & Order: Special Victims Unit” is a strong successor.

Another entry on the “Order” side of TV is the new CBS drama “Family Law,” premiering at 10 p.m.

The series stars Kathleen Quinlan (“Apollo 13”) as marital attorney and mom Lynn Holt, whose longtime husband announces out of the blue that he’s leaving her. Without telling her, he then sets up shop across the street, taking most of the clients, staff, assets and furniture with him.

Lynn finds herself having to rebuild, with the help of the one attorney who stayed, conniving and offbeat litigator Danni Lipton (Julie Warner, “Doc Hollywood”). The debut episode offers little information about the other two attorneys with whom Holt and Lipton become allied. Criminal lawyer Rex Weller, played by Christopher McDonald, has had his own problems, as his partners took off for Paraguay with the client trust account. Civil attorney Randi King, played by Dixie Carter (“Designing Women”), explains her strengths: “I hate men. And I play very dirty.”

“Family Law” uses the established TV-law pattern of heavy and light cases in its first episode. Holt helps an ex-junkie mom try to get her two boys back. Meanwhile, Lipton handles a divorce case where the couple is feuding over the ashes of their dog.

Executive producer Paul Haggis has a strong creative track record, with such worthwhile if underwatched efforts as “EZ Streets” and “Due South” on his resume. So while “Family Law” hasn’t shown much of itself in one hour, it’s a sure bet that, between Haggis and the talented cast, the show will realize its potential quickly.

CBS’ other newcomer, “Ladies Man” at 8:30, is ploddingly unoriginal. Its premise: one poor guy surrounded by female relatives. It’s not even the only new show this season with this concept (see ABC’s “Odd Man Out”).

“Ladies Man” also proves the old adage that it’s possible for the total to be less than the sum of the parts. Its executive producer is Chris Thompson, who must be devoting most of his attention to his new Fox series “Action.” The pilot is directed by veteran James Burrows, and the show’s cast includes Broadway-screen actor Alfred Molina and TV mainstays Sharon Lawrence (“NYPD Blue”), Park Overall (“Empty Nest”), Betty White (“Golden Girls”) and Dixie Carter again, in a recurring role.

And yet, following the lead of last season’s “Encore! Encore!,” this talented group is largely wasted in a paint-by-numbers sitcom. Neither Molina’s male victim Jimmy Stiles nor any of the man-hating female characters have anything new to offer about the condition of the American family. By aiming low, “Ladies Man” should successfully offend viewers of both genders.

Also debuting tonight is “Safe Harbor” at 9 p.m. on WB. The new family drama by “7th Heaven” creator Brenda Hampton, “Safe Harbor” tells the story of the sheriff (played by Gregory Harrison) of a small seaside town in Florida and the widowed father of three boys.

The entire family lives at The Magic Beach Motel, which has been converted into a residence. They are permanently joined by the youngest boy’s best friend, “his cosmic twin,” and a runaway teen girl, who gets placed into the sheriff’s protective custody.

“Safe Harbor” isn’t the guilty pleasure that “7th Heaven” is, and its tone swings wildly from cutesy to cop-show dramatic. Harrison (“Trapper John, M.D.”) is just too earnest as a father and a lawman. Rue McClanahan (“Golden Girls”) is thankfully toned down as the grandmother, but the boys are largely ciphers who add little to the mix.

Although painfully well meaning, and a great match with its lead-in, “7th Heaven,” “Safe Harbor” doesn’t figure to be any viewer’s port of call for long.