This new film by Roger Michell, who made the superb adaptation of Jane Austen’s “Persuasion” (1995) and the popular comedy “Notting Hill” (1999), is a throwback of sorts, but while that’s usually a bad thing, in this case it’s a surprisingly beneficial one. “Changing Lanes” is reminiscent of some of the best American movies of the 1950s–pictures like Sidney Lumet’s “Twelve Angry Men” (1957) and its like. We’ve not seen many such films since Lumet’s “The Verdict” (1982), which recaptured a good deal of the spirit of those Eisenhower-era exercises in moral debate but recycled it into a more modern, little-guy-against-the-system idiom. Usually when new films try to resurrect such themes, they wind up as crushingly heavy-handed and simplistic–the recent “John Q.” was a perfect example. But Michell’s film succeeds both as taut drama and as a thought-provoking examination of how ordinary people struggle with ethical dilemmas in their everyday lives. Narratively smart and technically savvy, it’s an intelligent, well-crafted story of a sort that studios rarely offer us nowadays.

The set-up is quite simple. Gavin Banek (Ben Affleck), a young, ambitious New York lawyer, is on his way to court to settle a dispute over whether his bosses will assume control over a multi- million dollar foundation by presenting papers proving that before his death its creator had signed it over to them (to his daughter’s dismay). Simultaneously Doyle Gipson (Samuel L. Jackson), an insurance salesman and recovering alcoholic, is traveling to the courthouse to represent himself in a divorce case; his wife is threatening to move to Oregon with their two sons, but Gipson has just arranged to buy a house which, he hopes will convince her to stay and try again. The two men get into a car accident on the rain-slick freeway, and though Gipson wants to do things by the book, Banek, in a rush, drives off, leaving the other man stranded. Gipson winds up late for his court session and loses his family. Banek, however, discovers that during their altercation Gipson has walked off with his most crucial file, without which the case–and perhaps his own career–will be doomed. The two men meet again (in an overly convenient coincidence), but though the desperate Banek begs the return of his papers, the furious Gipson refuses and taunts the young man. Before long Banek has engaged a sleazy computer hacker (Dylan Baker) to destroy Gipson’s credit as a means of pressuring him to return the file; Gipson angrily responds with a threat on Banek’s life, which the attorney counters with a virtual assault on Gipson’s family. It seems that the escalation is destined to end in tragedy.

If “Changing Lanes” merely recounted a tit-for-tat series of attacks and retaliations between a couple of cardboard characters, it might have had a crude emotional power but would have lacked dramatic weight–like Joel Schumacher’s meretricious “Falling Down” (1993), for instance. (Or, if treated comically, it might have developed into the sort of Laurel-and-Hardyesque confrontation that Thomas Berger, for example, has successfully contrived on the printed page.) But what scripters Chap Taylor and Michael Tolkin have done is to add an extra dimension by depicting the two men as complex, tormented individuals, torn between the urge to do what would seem effective or momentarily satisfying and the inclination to do what’s right. Despite the different races of the principals, neither is drawn in black-or-white; they both represent shades of grey. Banek and Gipson are essentially well-meaning but highly flawed people, whipsawed between self-interest and their natural tendency to be fair and honest. They have a reality to them that most Hollywood characters of today utterly lack.

And Affleck and Jackson portray them extraordinarily well. A subtle, shaded turn such as the one he offers here isn’t surprising coming from the latter–he’s proven himself on screen many times in the past–but for Affleck to achieve such nuance is a remarkable advance for him. Both men give rich, textured performances, and exhibit a convincing range of emotion. They work beautifully off one another, too. The thespian excellence continues into the smaller parts: Toni Collette is incisive as Banek’s ex-mistress and corporate conscience, while Amanda Peet is convincingly icy as his cold, pragmatic wife. Sydney Pollack is expertly sleazy as the lawyer’s boss (and father-in-law) Delano, as is Colm Feore as the older man’s greedy partner. And Kim Staunton has some quite touching moments as Gipson’s estranged spouse. Even William Hurt, in a virtual cameo as Gipson’s AA sponsor, is nicely restrained. From the technical perspective the film is excellent as well: Salvatore Totino’s cinematography gives the urban locations an appropriately gritty, downcast appearance, Christopher Tellefson’s editing keeps the pace quick and the narrative clear, and David Arnold’s music is suitably atmospheric. All of this abets Michell’s sure, skilled hand on the helm.

In fact, there’s only one problem with “Changing Lanes”–one that’s terribly common in today’s films: it goes soft at the close. That, of course, was the case with many of the ’50s pictures it’s emulating, but while in them it seemed a natural part of the message, here it merely comes across as a necessary sop to an audience that demands simple solutions. The final encounter between Banek and Gipson is too smooth and easy in view of the issues that have been raised, and it includes a monologue by Affleck entirely too derivative of the wonderful speech delivered by Everett Sloane in “Citizen Kane” (the one in which the elderly Bernstein recalls the girl he once caught a glimpse of on a ferry–Herman J. Mankiewicz and Orson Welles perhaps deserve a script credit here). The “toppers” which follow, in which both Banek and Gipson reach a kind of emotional apotheosis, are even more calculated to meet viewers’ expectations.

But in spite of these slips, “Changing Lanes” is probably as close to a serious, intense drama that a studio production can be in the present cinematic climate. It’s fairly dark picture, and its lack of clear-cut heroes and villains–its morally troubling, ambiguous underpinnings–will probably doom it to the same unhappy fate at the boxoffice that Sean Penn’s brilliant and similarly challenging “The Pledge” suffered last year. Nonetheless by Hollywood standards of today–and that overly uplifting ending apart (unfortunately it doesn’t share the courage of Penn’s film in extending its bleakness to the close)–this is a strong, truthful, and intriguing piece of work.