‘What’s Spike Lee going to have to say about this?” That was the first question on many minds after the initial shock of Green Book winning the best picture Oscar. We were just waiting for a reaction shot of Lee, applauding resignedly at history repeating itself. It was nearly 30 years ago that Lee was in a similar situation, when the anodyne, feelgood civil rights film Driving Miss Daisy won best picture, while Lee’s exhilarating Do the Right Thing went home empty-handed. Green Book was this year’s Driving Miss Daisy. While Lee’s considerably more confrontational BlacKkKlansman – also nominated for best picture – didn’t go home empty-handed, it must have felt like insult added to injury. According to the reporter Andrew Dalton, Lee was “visibly angry” at the announcement, “waving his arms in disgust and appearing to try to storm out of the Dolby theatre before he was stopped at the doors”.

Ironically, at first glance, Green Book and BlacKkKlansman have much in common. Both are set in the recent past and tackle US racism via a reluctant friendship between a black man and a white man. But where Green Book falls firmly into the category you could call “Isn’t it great how we’re not as racist as we used to be” movies, BlacKkKlansman concludes the opposite. Its sting-in-the-tail coda – footage from the 2017 white-nationalist march in Charlottesville, North Carolina, cheered on by the Ku Klux Klan – is a reminder that the US is every bit as racist as it used to be. Green Book finished with a wishful, small-scale racial truce; BlacKkKlansman delivered a harder, less convenient truth.

At the awards ceremony, Lee served a similar function to his movie. This time, at least, he received the Oscar for best adapted screenplay – and used his acceptance speech to inject a dose of bubble-bursting realism into a ceremony that seemed hell-bent on eradicating it. Lee invoked Black History Month, the genocide of Native Americans and the 400th anniversary of his ancestors arriving on American shores, “stolen from mother Africa and brought to Jamestown, Virginia”. He ended on an unambiguously current note: “The 2020 presidential election is around the corner. Let’s all mobilise, let’s all be on the right side of history. Make the moral choice between love versus hate. Let’s do the right thing!” Inevitably, Donald Trump tweeted back, complaining about Lee’s “racist hit on your president” and listing his own (self-identified) achievements for African Americans, as if there were any question over whose word African-American voters would trust more.

Adam Driver (left) and John David Washington in BlacKkKlansman. Photograph: David Lee/AP

Lee was not quite a lone voice in referencing politics at the Oscars, even if others did it more obliquely. Javier Bardem mentioned walls and borders (in Spanish) when presenting best foreign film to Alfonso Cuarón, for example, while Rami Malek spoke of his own and Freddie Mercury’s immigrant backgrounds. But the memo for this year’s Oscars seemed to read: “Political correctness: fine; actual politics: no, thanks.” In an Academy more hesitant than ever about what it is supposed to do or be, politics is now seen as a ratings loser. This is especially true after 2018’s ceremony, in which the presenter, Jimmy Kimmel, and various award-winners spoke directly about racism, gun control, sexual abuse, women’s rights, immigration and, of course, Trump. The conservative media – Trump included – were quick to equate the 2018 ceremony’s all-time-high political slant with its all-time-low television ratings. Anyone sticking their head above the parapet nowadays risks being labelled a pampered Hollywood liberal or a posturing bandwagon-jumper – everyone except Lee. Now more than ever, he looks and sounds like Hollywood’s political conscience.

You never feel as if Lee is auditioning for a political role ... He will speak his mind even when he knows he shouldn’t

Lee has always spoken out and never cared about the consequences. In the course of his career, on screen and off, he has denounced all manner of injustices, including police violence, gun control, Hollywood racism (witness his use of DW Griffith’s The Birth of a Nation in BlacKkKlansman), African-American self-caricature (he has a long-running spat with Tyler “Madea” Perry), and lack of representation within the industry.

In 2015, while receiving an honorary Oscar at the Governors’ awards at the height of the #OscarSoWhite debacle, Lee told his audience of Hollywood heavyweights: “Everybody in here probably voted for Obama, but when I go to offices I don’t see no black folks except for the brother man at the security.” The industry needed to have a serious conversation about diversity, he warned. “You better get smart, because your workforce should reflect what this country looks like.”

If the Academy thought they had brought Lee on side with the honorary gong, for his contributions to film-making, they were mistaken: Lee went on to boycott the Oscar ceremony proper a few months later, in protest at the lack of African-American nominees. In an open letter, Lee acknowledged his spokesman status, pointing out how his opinions were always sought when it came to Hollywood’s failings. “For too many years, when the Oscar nominations are revealed, my office phone rings off the hook with the media asking my opinion about the lack of African Americans,” he wrote. He advised people to ask the white nominees and studio heads instead.

Viggo Mortensen (left) and Mahershala Ali in Green Book. Photograph: Universal Pictures/AP

But in the absence of outspoken Hollywood figures, it has never mattered more what Lee has to say. After all this time, he has an authority and standing that few can match. His words matter – and he knows it. Yet you never feel as if Lee is auditioning for a political role or seeking publicity for its own sake (that said, respect for that purple, Prince-homaging outfit). It is more the opposite: Lee will speak his mind even when he knows he shouldn’t.

He did exactly that at the post-ceremony press conference, taking questions while admitting he was on his sixth glass of champagne. When someone asked his feelings about Green Book, he took several more swigs from his glass before answering. “Every time somebody’s driving somebody, I lose,” he joked, referencing Driving Miss Daisy.

But then, as always, Lee got real. He talked about Heather Heyer, the protester killed at Charlottesville, whose death is featured in the closing moments of BlacKkKlansman. “Her murder was an American terrorist act … and when the president of the United States did not refute, did not denounce the Klan, the alt-right and neo-Nazis … whether we won best picture or not, this film will stand the test of time, being on the right side of history.”

It was the second time that evening he used the expression. Throughout his career, Lee has variously been ignored, condemned and ostracised as much as he has been supported, applauded and admired. There is little doubt he is on the right side of history – and that is more important than any award.