Leering slave traders randomly shoot and flog their helpless, terrified victims. A woman gives birth in a mass of huddled humanity and the infant is passed from hand to hand so it can be lifted to the open air; a few scenes later, the mother slips over the ship's side into the sea, her child in her arms. A sack of stones is shoved overboard, and 50 persons, chained to it, follow. Those who survive the journey suffer the final indignation of being scrubbed clean to be paraded before the auction block and the parasoled gentry of Havana.

In its compressed intensity this segment eclipses even the relentless barbarism of Schindler's List; if for no other reason, Amistad deserves to be seen because it brings to life the obscenity of 400 years of slavery with the immediacy of a whiplash. Unfortunately, or mercifully, that is only 15 minutes in a two-and-a-half-hour movie. The rest is good-to-middling courtroom drama, period playacting, and civics lesson, animated by perhaps two Oscar-noteworthy performances.

The first is by Djimon Hounsou, who comes across as a force of nature as Cinque, the determined leader of the revolt and the focus of the subsequent trial. Captured with his fellows off the coast of Connecticut by the US Navy, he displays a ferocity and a thirst for freedom that are frightening and heartbreaking. Cinque's magnificent spirit notwithstanding, his fate and that of the other mutineers will be determined in a mere property trial. Among other suitors, 11-year-old Queen Isabella II of Spain (Anna Paquin, looking jaded and coltish in her finery) seeks to regain what she regards as her country's misappropriated goods.

On the Africans' side are two abolitionists out to advance their cause: Theodore Joadson (Morgan Freeman, vacantly distinguished), an ex-slave, and Lewis Tappan (Stellan Skarsgard in a footnote of a role), a wealthy merchant. To put forward their case they call on that venerable curmudgeon and human-rights advocate, ex-president John Quincy Adams (Anthony Hopkins as a crusty Yankee curio whom any minute you expect to say, "Pepperidge Fahm remembahs!"). Rejected by Adams, they turn to shady real-estate lawyer Roger Baldwin (Matthew McConaughey).

It's a good choice. His matinee looks rendered weasly by rimless spectacles and chin whiskers, McConaughey becomes an engaging study in good-natured self-interest; it's his best performance to date. Baldwin hopes to gain his clients' release through a technicality -- since only those born slaves can be considered as such, if he can prove the Amistad's cargo originated in Africa instead of Cuba, they are free men and their revolt against their captors is justified. In the course of preparing the case he learns Cinque's story, and the two grow testily close in the film's only example of character development.

That relationship becomes secondary to more pompous designs. Baldwin's strategy succeeds at the initial hearing, but higher forces are at work. President Martin Van Buren (Nigel Hawthorne) intervenes, partly to subdue rumblings of Civil War, but mostly to garner Southern votes in the upcoming election. As the case heads for the Supreme Court, the Amistad defense team prevails on the tiresome Adams, and all is neatly rapped up in a platitudinous speech and epilogue.

Which is a pity, because in addition to the slave-ship sequence Amistad shudders with images of disturbing genius, all shot by Janusz Kaminski in a monochromatic palette as stark as iron fetters. In a surreal moment, the newly liberated vessel passes within arm's length of another ship emerging from the mist, a ship where the passengers revel in fine dining and a string quartet. A vignette on cross-cultural communication almost emerges as Baldwin and company try to find someone who speaks Cinque's language by walking through the streets of New Haven counting to 10 in the prisoner's native Mandé. And few scenes in recent cinema pack the primal power of a tormented Cinque as he defies the court by repeatedly crying out, "Give us free!"

As was ultimately the case in Schindler's List, however, Spielberg's retort to the brutal crimes of history is glib, crowd-pleasing sentimentality. A passage in which a prisoner ponders illustrations in the New Testament while a judge ponders his verdict in a chapel would embarrass Harriet Beecher Stowe. And the metaphor of Adams nurturing the rose of freedom in his New England hothouse gets overripe fast. To his credit Spielberg has reopened the wound of this nation's greatest shame; the inadequacy of his efforts to bind it testify to its depth and virulence.