AS A FILM, the newly released"Ali" is riveting, but disappointing. Will Smith fails to capture the charismatic, larger-than-life energy of the extraordinary man who alternately mesmerized and antagonized the American public.

Still, it is worth seeing. Aside from watching the great boxer's lightening jabs and dancing feet -- and hearing early rhythmic sounds of rap -- this film has much to teach us about our country's recent history.

Forty years ago, Islam was an unfamiliar religion to most Americans. When the great boxer Cassius Clay announced his conversion in 1964, along with the new name of Muhammad Ali, his fans were simply stunned.

Why had an African American renounced a name just because his ancestors originally received it from a slave owner? Why had an urban black boxer become a Muslim? To many uninformed Americans, black Muslims seemed synonymous with black militants. The public grew scared. Had Ali become an advocate of violent revolution?

Four decades later, President Bush has just asked Muhammad Ali to star in a television spot designed to show the rest of the Islamic world that America welcomes Muslims, but not terrorists.

"Ali" also reminds us that the American system of justice, as flawed as it often seems, usually works. When Muhammad Ali refused -- for both religious and political reasons -- to go to Vietnam, he faced five years in prison and lost his boxing license, as well as his title as the world's heavyweight boxing champion.

The government vilified him as an unpatriotic draft dodger. Huge legal expenses, coupled with a long absence from the ring, cost him his livelihood. But instead of fleeing the country, Ali remained to fight for justice right here, in the United States.

To everyone's surprise, the Supreme Court eventually overturned his conviction and upheld his religious and political right to dissent from his government's policies. Once again, Ali was free to box -- and regain his title.

On a more ominous note, an important warning lurks within Ali's remarkable story. Because of his dissenting beliefs, he was relentlessly hounded by the FBI, who tapped each phone call and tracked his every movement.

Today, Ali is a national icon, revered for his great talent and honored for the life he has lived with such conviction.

Now, when our government has heightened its surveillance of civilians and the attorney general has equated dissent with a lack of patriotism, it is worth remembering that Muhammad Ali was once unjustly persecuted as an enemy of the state.

This article first appeared in the San Francisco Chronicle and is reprinted with permission.