starstarstarstar-half(3.5 stars)

At least two brilliant films have been made about the antiwar demonstrations and police riots that took place at the 1968 Democratic National Convention in Chicago. Haskell Wexler’s “Medium Cool,” released in 1969, blended documentary footage with a fictional story to create a vividly immediate sense of the twitchy unease and ultimate anarchy that ensued during those August days. In 2007, the filmmaker Brett Morgen revisited the trial of several activists who were accused of conspiracy and inciting a riot in his masterfully executed animated nonfiction film “Chicago 10.”

With “The Trial of the Chicago 7,” writer-director Aaron Sorkin delivers a more straightforward but no less stirring re-creation of an episode that can't help but feel timely in an era when America is riven by polarization not seen since the 1960s. (Sorkin’s seven refer to the defendants who were left after one of them, Black Panther Party co-founder Bobby Seale, was severed from the trial; Morgen also included the activists’ lawyers, William Kunstler and Leonard Weinglass.)

Briskly paced, bristling with Sorkin’s distinctive verbal fusillades, seamlessly blending conventional courtroom procedural with protest reenactments and documentary footage (including Wexler’s), “The Trial of the Chicago 7” offers an absorbing primer in a chapter of American history that was both bizarre and ruefully meaningful. The fact that it's also a showcase for some of the most dazzling performances on screen this year elevates it beyond mere history lesson and into something far more animated, exciting and viscerally entertaining.

Echoing Spike Lee’s “Da 5 Bloods” this summer, “The Trial of the Chicago 7” opens with a helpful refresher course on why 1968 was such a pivotal year: With Lyndon Johnson having increased troops in Vietnam and casualties growing by the day, a loose coalition of groups — including the Students for a Democratic Society, the Yippies, the National Mobilization Committee to End the War in Vietnam and others — descended on Chicago to protest the presumed Democratic nominee, Hubert Humphrey, who had supported Johnson’s escalation. Thankfully, Sorkin doesn't dive right in to the bloody clashes between demonstrators and Chicago police that left hundreds seriously injured. Rather, he begins in the office of U.S. Attorney General John Mitchell (John Doman) who, a year after the events, is determined to punish the subversives by way of a federal trial.

What transpired over the next five months was an almost surreal piece of long-playing political theater, as Yippies Abbie Hoffman and Jerry Rubin (Sacha Baron Cohen and Jeremy Strong), SDS leaders Tom Hayden and Rennie Davis (Eddie Redmayne and Alex Sharp), veteran peace activist David Dellinger (John Carroll Lynch) and the now almost-forgotten Lee Weiner and John Froines (Noah Robbins, Danny Flaherty) watched as an addled judge named Julius Hoffman (Frank Langella) heaped contempt charge upon contempt charge on them and Kunstler (Mark Rylance).

Not that Judge Hoffman wasn't often provoked: While Hayden tried his best to play it straight, believing reason and rectitude could win over the jury, Abbie and Jerry used the courtroom as a backdrop for profane improv and antic agitprop, arriving one day in judicial robes (under which they wore Chicago police uniforms), and on another with a birthday cake. As if the obvious bias of the judge wasn’t challenging enough, the defendants — especially Hayden and Hoffman — were squabbling among themselves over tone, tactics and revolutionary bona fides.

It was a circus — of justified outrage, sometimes fuzzy idealism, youthful swagger and misjudged hubris, and also of breathtaking judicial bias that bordered on incompetence. At one of many low points Seale, portrayed in a commanding performance by Yahya Abdul-Mateen II, was famously bound and gagged by Judge Hoffman after his repeated (and justified) outbursts protesting his lack of counsel, which are re-created here with excruciating detail. He was finally separated from the proceedings, but only after the brutal murder of fellow Black Panther Fred Hampton (Kelvin Harrison Jr.).

There are so many characters to keep track of in “The Trial of Chicago 7,” so many swirling agendas and rivalries and sidebars and surprising doglegs (Michael Keaton shows up late in the film as former U.S. attorney general Ramsay Clark), that a linear, Wiki-like narrative would seem to be a filmmaker’s only recourse. But Sorkin’s mastery of the material, and his shrewd instincts as a dramatist, result in something much more fluid and emotionally engaging than a mere fact-based retelling. He has cast his film impeccably, with the actors confidently toeing the line between impersonation and characterization. Redmayne and Cohen are particularly impressive as activists with wildly different approaches to social change. (Much like his character, Langella continually threatens to steal the whole show with his magnificent portrayal of the other Hoffman, whose imperious disdain for the defendants is only equaled by his obliviousness and confoundment.)

“The Trial of the Chicago 7” takes its share of liberties, especially when it comes to its more irresistible movie moments. Sorkin wisely leaves out the parade of celebrities Kunstler called as witnesses, including Judy Collins, Arlo Guthrie, Allen Ginsberg and Norman Mailer, who famously said that the genius of the protesters was that they realized they didn't need to “attack the fortress.” All they had to do was “surround it, make faces at the people inside and let them have nervous breakdowns and destroy themselves.”

Instead, Sorkin also goes out of his way to play up the bromance that is simmering just under the friction between Hayden and Hoffman, the latter of whom delivers an admiring assessment of his co-defendant (and strategic adversary) that sounds more “West Wing” than “Steal This Book.” But the movie also reminds viewers just how intelligent Hoffman was beneath the tie-dye headbands and sophomoric pranks. Intercutting moments from the speaking gigs Hoffman performed on campuses throughout the trial, Sorkin reveals someone far more thoughtful and widely read than the somewhat frightening frizzy-haired enfant terrible of public memory.

But is there public memory of Abbie Hoffman anymore? While baby boomers and
Gen-Xers might watch “The Trial of the Chicago 7” with a mix of nostalgia and regret, one wonders what today's generation of activists will make of seeing this pageant of mass dissent, institutional backlash, internal factionalism and precarious moral victories. The whole world was watching then. Today, the whole world is scrolling. Sorkin knows better than to compare explicitly the two eras and their respective social movements. Instead, he leaves it to the audience to decide where we are, where we’ve been and how much further we need to go.

R. At area theaters. Contains coarse language throughout, some violence, bloody images and drug use. 129 minutes.