Like many upbeat biographical dramas, “I Swear” begins at the end. A culminating moment of triumph is neatly reverse engineered into a prologue: it’s 2019, and the Scottish activist John Davidson (Robert Aramayo) is being honored for his groundbreaking work to raise awareness of Tourette’s syndrome. John is nervous, for good reason. He has severe coprolalia, a symptom of Tourette’s that causes him to blurt out obscenities unpredictably—all in all, not an ideal situation for a man about to meet Queen Elizabeth II. Sure enough, John causes a scene, yelling, “Fuck the Queen!” Once the initial shock in the room has subsided—the Queen herself seems unperturbed—John says, “Sorry, Ma’am,” and quietly finds his seat. The ceremony begins, and the message is clear: if Her Majesty could take such an indignity in stride, what’s the rest of the world’s excuse?

It’s an amusing point of entry, although, as a scene of comic vindication, it arguably renders the movie moot. Here is Davidson in a foul-mouthed nutshell: sincere, self-effacing, and prone to embarrassing exclamations that—even after years of anguished personal struggle and laudable public advocacy—he remains powerless to prevent. The film’s title, an obvious reference to profanity, also alludes to an incident dramatized later on, when John, on trial after inadvertently triggering a pub brawl, must give sworn testimony in court. (He can’t get through the oath without calling the judge a cunt—an assessment as unintentional as it is hilariously spot-on.) What’s a man to do when, in striving to tell the whole truth and nothing but the truth, his best-faith efforts are mistaken for the opposite?

“I Swear” serves up an ingratiating answer to that question. It was written and directed by the British filmmaker Kirk Jones, a reliable purveyor of uplift; only in comparison with his earlier work, which includes “Waking Ned Devine” (1998), “Nanny McPhee” (2006), and “My Big Fat Greek Wedding 2” (2016), could his new movie be construed as remotely hard-hitting. With its mostly happy ending established, it flashes back to 1983, when the teen-age John (played movingly by Scott Ellis Watson), who lives with his parents and siblings in the Scottish town of Galashiels, begins to experience his first Tourette’s symptoms. His physical tics derail a promising football career, and his verbal eruptions frequently land him in trouble at school, where neither his peers nor his headmaster grasp that he has no control over his offending words and deeds. Even a deeper knowledge of Tourette’s is not a guarantee of understanding. When John begins spitting out his food, his mother, Heather (Shirley Henderson), worn down by exhaustion and anger, banishes him from the dinner table—the first in an unceasing series of maternal rejections. (His father’s rejection is more final; he abandons the family not long after John’s condition worsens.) Years later, only John (now played by Aramayo) remains with Heather at home, medicated into semi-submission, with little hope of a life of independence or fulfillment.

John Davidson’s story has been told in several TV documentaries over the past few decades, starting with a 1988 episode of the BBC series “Q.E.D.,” titled “John’s Not Mad,” which has been credited with doing much to educate the British public about Tourette’s. (Oliver Sacks, one of the episode’s prominent voices, offers a precise, sympathetic analysis of John’s symptoms.) Perhaps because it focussed on John’s teen-age years, when Tourette’s treatments and therapies were fewer and farther between, the documentary took a more downbeat view of its subject and his prospects than the movie does. In “I Swear,” John’s social rehabilitation is set in motion by Dottie Achenbach (Maxine Peake), the mother of an old school friend, who takes John under her wing. In relatively short order, she moves John into her house, gets him off his meds, and encourages him to apply for a job at a local community center, where his boss, Tommy Trotter (Peter Mullan), proves as saintly as Dottie is. It’s Tommy who nudges John toward the realization that the problem lies not with his condition but with society’s ignorance of it. A public-awareness campaign is launched, with John heroically leading the way.

“I Swear,” then, isn’t just an account of Davidson’s life. It’s a direct extension of his activism, and its effectiveness as an educational tool is what renders it frictionless and predictable as a drama. In the course of the narrative, as John is embraced by friends and assaulted by strangers, Jones’s storytelling veers between breakthroughs and setbacks with a rhythm so mechanical as to verge on metronomic. Yet the movie is a slick and expertly calculated piece of work, and it has taken even the most reflexive skepticism into account; you may emerge from the theatre blinking back tears and rolling your eyes. The only remotely complicated figure is his mother, Heather—a would-be villain in the logic of the film, made more complex and tragic by Henderson, who has a gift for gloomy nuance. Strikingly, in “John’s Not Mad,” the real-life Heather came across as entirely devoted and sympathetic. You needn’t be a bio-pic truth fetishist to wonder how close to reality Jones’s treatment gets—and how much may have been artificially sweetened, or embittered, for effect.

Aramayo’s role raises other questions. Some people may have strong feelings about the ethics of an actor who does not have Tourette’s performing the tics and gestures that accompany the condition; as it happens, I was disarmed by the friendly jut of Aramayo’s smile and the gentle clownery of his carriage. He strides through the movie with a startling mix of awkwardness and grace: the light-footed assurance of someone who has learned to anticipate—and perhaps overcorrect for—errant movements.

For me, the possible false note lay not in Aramayo’s performance but in the script. At times, it seems that Jones’s film, far from being strictly diagnostic, might in fact be egging John on, for the sake of our entertainment, toward perverse new heights of verbal invention. After brewing a cup of tea for Tommy, John blurts out, “I use spunk for milk”—and spunk, more in the spiritual than the bodily sense, is what the movie has in spades. Its humor is so insistent that it’s almost unseemly, transforming “I Swear” into a curious kind of misfired-synapses comedy—one that, in tone and intent, seems to fly in the face of the sombre warning issued by the 1988 documentary: “John’s obscenities will always be a verbal time bomb, waiting to go off in public.”

That grim prophecy was fulfilled—and how—on February 22nd, at the BAFTAs, where “I Swear” experienced a one-of-a-kind commingling of glory and disaster. To the shock of many, Aramayo won Best Actor, triumphing over a field that included the Oscar nominees Timothée Chalamet, Leonardo DiCaprio, Ethan Hawke, and Michael B. Jordan. Davidson was in the crowd, too, as the audience had been informed, with an announcement that any outbursts they might hear from him were involuntary and not representative of his views or beliefs. The warning proved scant consolation when Davidson shouted a racial slur at two Black actors—Jordan and Delroy Lindo, both from “Sinners”—who were presenting an award onstage. The BBC inexplicably neglected to excise the incident from its tape-delayed broadcast of the ceremony, and, amid the ugly fallout, much was written about the failures of the network and of BAFTA in their duty of care to all involved. More divisive has been the question of who, in the end, was the more aggrieved party: Jordan and Lindo, who were subjected to unconscionable humiliation, or Davidson, who was accused of racism online by countless individuals with no understanding of or empathy for his condition.

What makes the episode worth considering anew, as “I Swear” arrives in American theatres this month, is how it seemed to both destroy and affirm the film in one nightmarish breath—to expose the hollowness of its feel-good machinery while also proving its larger point about the vindictive ignorance of so much of the public. There’s a particularly hideous irony in the fact that “I Swear,” which depicts a fictional Davidson prevailing through some of his gravest anxieties, wound up thrusting the real Davidson into the most public embarrassment of his life. What horror! But also, for sheer educational and entertainment value, what an opportunity. Had the filmmakers been inclined to tweak their work at the last minute, they might have reshot their prologue, guerrilla-style, ahead of the film’s U.S. release. Who needs a mild anti-monarchist outburst, given the far thornier international debacle on the BAFTAs stage? Fuck the Queen, indeed. ♦