"The Practice" also earned James Spader a lead acting Emmy as oddball attorney Alan Shore, and he, too, has joined "Boston Legal's" international law firm, Crane, Poole & Schmidt.

Both shows, as well as that former iconoclastic legal series "Ally McBeal," were created by David E. Kelley, who wrote the quirky Crane character with Shatner in mind.

Unlike his forever-famous role as Capt. James T. Kirk of "Star Trek," Shatner says his latest TV persona leaves us guessing whether Crane is in full command.

"I think that we don't know whether he's dumb or smart, whether he's cunning or stupid, whether he knows what's going on all around or is totally unaware. I think that's part of the fun of playing it," says the veteran actor.

"Standing on the set when that collision of actor and role happens, when it's such a perfect fit — that's the kind of thing you live for," says Bill D'Elia, executive producer and director of "Boston Legal."

The series airs Sundays on ABC, and is filmed on sets built at Kelley's production facility in Manhattan Beach, just south of Los Angeles International Airport.

The upscale law firm's huge suite of lush, airy offices — all glass and cherry and birch — are incomes away from the dark and cramped workspace of "The Practice."

"Everything is lighter, faster, funnier, jazzier, with a visual style to match that," says Shatner, who is described by D'Elia as "just a blast ... a force of nature."

Indeed, even chatting off camera, the 73-year-old actor exudes energy. He needs it, as he continues one of Hollywood's more dramatic comebacks.

Besides the long hours of a regular series, he's got another of his "Star Trek" novels to promote, his self-mocking "Has Been" CD to sell and those Priceline commercials to shoot.

There are even horses to drive — Shatner just returned from winning a fine-harness world championship at the Kentucky State Fair.

Reflecting on keeping control when driving a horse — as opposed to riding, which he also does — Shatner says "it could be termed an old man's art, but in this case it took a lot of muscle ... it's like having a coiled spring.

It's compressed, and you have to know when and how much to let it out."

Moments later, observing the actor's perfect timing and control while doing a scene as Crane, that description could also apply to his talent as a performer.

His secret?

"I'm trying to make it fun because acting should be playing, and you're at your best and most at ease when you are playing," Shatner says. "The hours are long and the drill of learning lines is difficult, but I wouldn't call it hard work. Coal mining is hard work."

After his "Star Trek" series years, he was the title character in six seasons of the cop show "T.J. Hooker." He also starred in seven "Star Trek" movies and directed the fifth, "The Final Frontier."

"In a strange way, I think being on stage for an hour, an hour and half, not knowing what I am going to say next, having to react with total spontaneity answering questions, sharpens my mind in terms of repartee, comebacks, inventive stories, the whole creative process," he says.

"It's a help in learning to stay entertaining."

Shatner is the father of three grown daughters and three times a grandfather. His third wife, Nerine, drowned in their swimming pool in 1999. He's now married to Elizabeth, a fellow horse enthusiast.

He points to his wedding ring, noting that his reluctance to ever take it off is one reason the nature of Crane's own private life is still in creative flux.

As to life's ups and downs, Shatner feels he's suffered "no more or less than anyone else."