A little-noticed treasure fell into the laps of movie-lovers amid the hullabaloo of year-end top 10 lists and Oscar bait. Frederick Wiseman’s massive, moving chronicles of America, its people, and its institutions have long been elusive after initial television broadcasts and theater runs, unless one was willing to scour library collections. But the recent release on DVD of 23 documentaries by the great filmmaker finally makes widely available an essential piece of movie history and American society and culture.

For a peerless, foundational oeuvre that raises comparisons to everyone from Walker Evans to Balzac, the delay has been hard to fathom, but such are the trials of film distribution.

“Nobody wanted to put out all the films,” Mr. Wiseman, who turned 78 on New Year’s Day, said via cell phone during a forest hike in Switzerland. “I wanted all of them out.” The Massachusetts-born filmmaker, whose most recent film, 2006’s “State Legislature,” made its premiere last summer on PBS, is releasing the DVDs through Zipporah Films, the same company that has handled his theatrical distribution for more than 35 years. (The discs are available for purchase at zipporah.com. Additional titles are planned for release later this month.)

The titles of Mr. Wiseman’s 30 movies — including “High School,” “Welfare,” “Domestic Violence,” and “Central Park” (all to be released) — typically sound droll with understatement compared with the worlds they offer onscreen. Filmed in a focused vérité style yet carefully constructed, each documentary is at once a collection of intimate vignettes, a detailed portrait of an institution, and a time-capsule record of human behavior, speech, and dress. Compassion, suffering, excitement, tedium, the eloquent, the ugly, and the ordinary all pass before Mr. Wiseman’s measured, humanist gaze.

“I’m trying to put you, the viewer, in the middle of these events and ask you to evaluate them based on your own experience,” Mr. Wiseman said. His deliberate approach, unadorned by voiceover or heavy-handed cues, is a far cry from many documentaries today and their niche-audience appeal, titillating directorial involvement, or ostentatious backstories.

A prime example of Mr. Wiseman’s approach is 1975’s “Welfare,” his black-and-white look at New York’s system of governmental support. Shooting entirely within the city’s Jay Street welfare offices, Mr. Wiseman observed encounters between institution and individual, from a heartbreakingly fretful homeless woman to a shifty sort-of couple to an unremarkable pregnant woman who is simply broke and ignorant of free clinics. Close-ups deepen each personal drama, with regular respites to the waiting room and the social workers on their own time.

Workers and clients alike fight through the absurd blizzard of bureaucracy, alternating among arias of confusion, interpretation, and explanation. It’s part pageant of humanity, part laboratory of social discontent, often placing the viewer in the challenging position of skeptic and supporter. Scenes that are richer or stranger than fiction arise regularly, like the winding, apocalyptic chat between a white, racist ex-World War II gunner and a bemused black cop.

Red tape is not the first subject one might consider for a movie, but Mr. Wiseman has long been drawn to what is unexamined but in plain view. “It seemed to me there were many aspects of the world that hadn’t yet been explored on film,” said the director, who began filmmaking after only a brief career in law (he is a member of the Massachusetts Bar Association), right around the revolutionary rise of liberating synch-sound equipment.

Mr. Wiseman’s legal skills came in handy for his debut, the 1967 landmark “Titicut Follies,” a stark and disturbing examination of the Bridgewater, Mass., State Prison for the Criminally Insane, which became tangled up in a long-running court battle. Embarrassed state officials, who were at first proud of the work depicted, quickly panicked when early viewers were shocked about the behavior of some guards in the film, not to mention the catatonic inmates, confined to unlit cells, who are only occasionally rinsed with a hose and taken out for force-feeding.

The film’s distribution was banned in America between 1967 and 1992 by the Massachusetts Supreme Judicial Court, which ruled that since “Titicut Follies” was filmed in a hospital, it violated the patients’ rights to privacy. Unavailable for years, the film was finally allowed to be broadcast in 1992, and it is among the new releases on DVD.

“The case didn’t bother me so much as the fact that a lot of friends abandoned me,” Mr. Wiseman said. “That was the worst part of it. The case was ridiculous. I fought it hard and I lost, but 24 years later, I won.”

Mr. Wiseman’s tenacity has made him perhaps American cinema’s most enduring independent filmmaker, partly due to his cautious control of distribution. He set up Zipporah Films, he said, after the distributor of “Titicut Follies” and “High School,” Grove Press, withheld his profit share until he sued. And Mr. Wiseman avowedly views DVD distribution in terms of economic self-sufficiency.

“I never got a decent offer from a DVD distributor,” he said. “And I, like other documentary filmmakers, like to eat and make more movies.”

Bolstered by steady funding from public television, Mr. Wiseman has averaged almost a film a year since 1967, a remarkable pace given the scale of each endeavor. “State Legislature,” for example, his study of Idaho’s citizen legislature, took 11 weeks to shoot and yielded 160 hours of raw material. Mr. Wiseman molded the footage during seven months of initial editing, followed by further assembly and harmonization of sequences.

His preparation, however, is comparatively brief: “I try to get a sense of the geography and what the centers of power are,” he said. “The shooting of the film is the research.”

But a perpetual challenge, even before shooting, involves obtaining permission from subjects who rarely receive such scrutiny on film. After decades of practice, Mr. Wiseman obviously has a knack for getting his foot in the door.

“It’s the kind of situation where ethics and tactics coincide,” he said. “The ethical thing to do is to be straightforward, but tactically that’s also the smartest thing to do.”

Though generally protected by the First Amendment when filming public institutions, the filmmaker ran into trouble in 2006 with “The Garden,” about a short period in the life of Madison Square Garden. It remains in legal limbo, blocked by Cablevision, which owns the arena.

Despite the occasional obstacle, Mr. Wiseman maintains a pace and a level of quality and rigor that are hard to match. “A lot of my movies are organized in part around the theme of work,” he said, and one can’t help noticing that his own work ethic is as epic as his films. And Mr. Wiseman, whose father practiced law for 60 years, shows no signs of slowing down. In 2006, he even directed and acted in a production of Samuel Beckett’s “Happy Days” at the Comédie Française. Now, with his years of American chronicles committed to DVD, the rest of us can at last try to catch up.