"I think peacock is a word I'd put out there," says Kyle MacLachlan in describing the sartorial style and elegant physical strut of David Swain, the maverick attorney he plays in ABC's new legal series "In Justice," premiering Sunday at 9 p.m.

Swain heads a nonprofit association of lawyers and private investigators working to overturn the sentences of the wrongly convicted. Yet for most of this day on the Culver Studios set, he's been locked up himself — jammed into a crowded holding cell for contempt of court.

Dressed as Swain in a smartly tailored business suit — his dark hair thick and shiny enough for any shampoo commercial — MacLachlan exudes energy and enthusiasm as he works out complex moves with director Steven DePaul and fellow cast members, including Jason O'Mara as Charles Conti, an ex-cop turned private investigator.

O'Mara says the scenes between Swain and Conti are "really the crux of the show. The way we relate is what gives it its sparkle." He notes that the two actors "like to think it's sort of Butch and Sundance."

MacLachlan, 46, first became known when he was picked by David Lynch to star as the heroic Paul Usul Muad'Dib Atreides in the 1984 filming of the sci-fi epic "Dune." Although that movie was a dud, Lynch employed MacLachlan more memorably as the young sleuth in the quirky "Blue Velvet" in 1986 and most famously of all as FBI agent Dale Cooper in the oddball 1990 TV serial "Twin Peaks."

As time went by and MacLachlan's efforts to find another quality TV series failed, he "started realizing that 'Twin Peaks' was very special. I didn't realize that at the time. I thought, 'Oh this is easy.' "

More recently — and successfully — he was a regular for several seasons on HBO's "Sex and the City" as Charlotte's ideal man, Dr. Trey MacDougal. His equally eccentric film career includes the box-office bomb "Showgirls," the digital experiment "Timecode" and, most recently, "Touch of Pink," in which he plays the spirit of Cary Grant.

With hindsight, MacLachlan notes that even a good idea backed by excellent casting and fine writing isn't likely to work as a TV series if it doesn't hit "a core issue" that audiences can grasp. The "In Justice" exploration of the plight of innocents wrongly convicted strikes him as being in tune with the times.

"I don't know if maybe it's just me that's aware because of researching this show, or that there really is more news coverage of these sort of cases," he says. "But I feel it is very current, and that we may be riding a crest of a wave."

He also says he thinks the series will stand apart from the glut of other crime and legal shows because it's about getting mistreated people out of jail rather than about chasing down bad guys and locking them up.

As a lawyer going up against the law, Swain could be viewed as a morally ambiguous character.

MacLachlan says he changes his opinion all the time about Swain's motivations. "Fortunately, the writers are clever enough to never really answer that question and, hopefully, they never will, although we get hints about it ... probably if you asked him what he believes in he'd give you a different answer every day."

To add to that uncertainty, says MacLachlan, "I'm making him deliberately difficult to get a bead on."