Boxing is the proverbially dirty game, life an even nastier one. Voted with Robert Flaherty “the [two] most influential documentary makers” ever, New Hampshire-based Ken Burns repeatedly examines life in these United States, famously through sports, music and politics, and finds it rooted in the unclean open secret of racism.

Through his Florentine Films, the director’s newest entry in twenty-three years of award winners, is Unforgivable Blackness: The Rise and Fall of Jack Johnson, one of six Special Events at the current New York Film Festival, where it is co-presented with Jazz at Lincoln Center and will air on PBS January 17 and 18 next. It is not the same experience, and unfair, to judge big-screen film from a TV viewing; equally difficult to appraise shorter television episodes combined in the theater as a 110-minute Part One “The Rise,” a brief coffee break and then the ten-minutes-less second part “The Fall.”

The continuous theatrical screening, as opposed to choppier home viewing, underscores emotional buildup and social backbone yet at the same time introduces, or emphasizes, drawbacks such as repetitiousness as the same point is hammered again and again. With the usual impeccable research, organization and smooth incorporation of music (Wynton Marsalis) and rare film material, Burns employs his core story to manage a portrait of society over a period of years. Fallen into oblivion among today’s younger generation, John Arthur “Jack” Johnson surfaced on late ‘60s Broadway with Howard Sackler’s The Great White Hope, re-scripted by him for Darryl Zanuck’s financially unsuccessful 1970 film. Not a boxing story, or even social commentary, that tale of “Jack Jefferson” was at heart a character study, an aspiring Aristotelian tragedy down to its black Tiresias who warns star James Earl Jones against selling out.

Unforgivable Blackness, in contrast, focuses half on the Galveston, Texas, heavyweight who changed the manly art with an Ali-like combination of art and power, was unbeatable for thirteen years, in 1908 became at thirty years nine months the first -- for many years, only-- black champion at any weight, and aroused the anger, envy and sometimes vengeance of most whites worldwide and of many “so-called decent, middle-class black people.”

The film opens in 1910 Reno, population 15,000 and vying with Goldfield for status, where in the “Battle of the Century” the African-American champion would face undefeated ex-titleholder Jim Jeffries, goaded from retirement as the best of suggested great white hopes. Interspersed with interviews with several modern commentators (including Jones), the documentary traces Johnson’s beginnings and life up, and subsequent, to that point, placing them in the context of prevalent racist attitudes and laws.

During intermission, a German-accented lady marveled at these revelations of discrimination, which should be sadly familiar to Americans even if much of the archival material itself is not. Johnson attracted enmity because his ring prowess contradicted stereotypes of all colored races as “yellow” and further outraged the righteous by an ostentatious show-biz lifestyle. The final straw was his openly living with a harem of white women, two of whom eventually became his wives, which sexual “transgression” would lead to an unscrupulous but successful legal attack by way of the Mann Act.

To narration by Keith David and with Samuel L. Jackson as the voice of the boxer’s sensitive and learned 1927 autobiography, this proud man who would live life his way, emerges. His approach was not that of a crusader for equality on a racial basis but on the level of each individual. If the background of Jim Crow, lynchings, race riots, abusive epithets and media and government collusion, comes as revelation, that is the failure of our attitudes and educational system. The film’s assertion that the exiled Johnson did not throw the 1915 Havana fight against white hope Jess Willard is new, though perhaps debatable, and the jerky “stretched” record of that fight and others is a discovery, along with information about fight-film sales nearly a century ago. The subject is admirably served here, and one hopes that his unique person and contribution will at last be recognized. In large-screen continuous format, however, the social theme becomes unnecessarily redundant, and this is a case where less would have been more.

(Released by Florentine Films; not rated by MPAA.)