Reportedly shot over a 16-year period, director Tony Kaye’s Lake of Fire may be the most comprehensive documentary ever made about abortion in America. As divisive as it is meticulously two-sided, it is a film of intricate ideas and ideals, homing in on the moment of conception for the anti-abortion crusade in the United States. In its somewhat self-conscious black and white, Lake of Fire attempts to open a dialogue in the grey area between two factions who can’t seem to hear -- much less understand -- each other. There are decisions to be made, Kaye's subjects note throughout the film's 152-minute running time, and the parameters of the sanctity of life are somewhere between a woman washing the (potentially life-giving) cells off of her hands and infanticide. How can we make sense of the abortion issue -- personally, philosophically, legally, ethically, religiously -- and its role as a flashpoint for so many even deeper, more complex divides forming in this country?

Kaye, a native Brit, attempts just that by assembling commentators like Alan Dershowitz, Nat Hentoff and Noam Chomsky to unpack the elements of a debate in which everybody -- to some degree -- is right. Our values are not absolute; life should be valued but is it relative? Context-dependent? Their thoughts are wrapped around events largely taking place in the 1990s, beginning with President Clinton’s rollback of Reagan-era abortion restrictions in 1993. (This year’s other abortion documentary, Unborn in the USA, features the contemporary conflict in full fruition.) Profiling anti-abortion activists like Paul Hill, John Burt and Randall Terry, Kaye follows the movement from its gnarly fundamentalist roots (the most zealous of this faction are male, usually born-again Christians and/or reformed addicts of some sort) into a crusade unafraid of using extreme violence to enforce its beliefs. The clinic bombings and assassinations (whose horrific images function in counterpoint to the film’s many shots of dismembered aborted fetuses, and witness to its exploration of life’s intrinsic value) that ensue both embolden the crusaders and rattle the other side; fewer and fewer doctors are willing to put their lives at risk.

Confusing as it can be, dipping back and forth in time with few to no guiding dates, Kaye's timeline ultimately emphasizes the reminder that so many of rapturous predictions on display here have come to pass; the religious right has used abortion as a key conversion issue and an essential way to raise money. There exists perhaps no better metaphor for this phenomenal transformation than Norma McCorvey, aka Jane Roe, whose 1973 Supreme Court triumph in Roe vs. Wade legalized abortion throughout the United States. Kaye finds McCorvey in Texas, where she tells of the persecution she faced for years from anti-abortion activists and how she wound up working in an abortion clinic herself. After the release of her first book in 1994, she was confronted by Operation Rescue activist Flip Benham; in less than a year she was baptized, born again and indoctrinated into the pro-life movement. By 2005, McCorvey was petitioning the Supreme Court to overturn the decision in her case -- to no avail.

Lake of Fire never drags, though it feels slightly less focused in its final 20 minutes. Decidedly non-partisan in approach, even when Kaye missteps he seems to do it in equal measure -- first focusing in on the unstoppably flapping lips of an evangelical minister as he raves about the children and Jesus and that inevitable lake of fire, then making a bizarre stop to watch an anomalous rock band fronted by an angry, topless, leather-thonged woman who angrily simulates penetration with a coat hanger. Nevertheless, when Kaye finally moves into the story of 28-year-old Stacey -- the second abortion he will document in graphic detail -- his editorial counterpoints feel more forced in their momentum, building as they do to the film’s second shot of a vagina propped open with a speculum and shortly thereafter, a technician fingering through the viscera of a fetus.

A bid for the sensational in a film that spent the previous two hours walking a humble line, surely the sequence does more harm than good for any viewer who has gone through such an experience (almost 1.3 million American women had abortions in 2005), and the final dive for pathos in what had been a thoughtfully removed -- often highly intellectual -- and wrenching presentation is jarringly dramatic and voyeuristic. When Kaye sits the bedraggled Stacey in front of the camera moments after she is out of the stirrups and basically waits for her to crack during a long, steady take, the word that comes to mind is "pornographic"; what a shame for Stacey and for this very fine film.