NEW YORK, UNITED STATES -- Celebrities, brands, leaders and ordinary people are all falling foul of "cancel culture," a movement that seeks to call out offensive behaviour but that critics denounce as excessive and contributing to increased political polarization.

Whether it's a controversial tweet or video clip, social media users are quick to demand accountability -- but detractors say it can amount to online shaming.

"Cancel culture" involves a concerted effort to withdraw support for the figure or business that has said or done something objectionable until they either apologize or disappear from view.

Author JK Rowling, for comments deemed deeply insulting to transgender people; YouTuber Shane Dawson, for old videos of him in blackface; and singer Lana Del Rey, for a controversial Instagram post contrasting herself with black artists, have all been caught in the wave.

Brands are also being forced to react so as not to lose customers: for example, Uncle Ben's and Aunt Jemima for their use of African-American mascots widely considered to be racist caricatures that have long been taboo.

Richard Ford, a law professor at California's Stanford University agrees that "some of the social media activism is constructive and legitimate" but also warns of "reflexive campaigns and crusades" online.

"Activism on Twitter is easy: it takes a couple of seconds to attack someone or circulate a petition to have the person fired or ostracized," Ford told AFP.

The academic was one of roughly 150 personalities from the world of arts and sciences to sign a letter published on the Harper's magazine website earlier this month that complained that cancel culture was restricting debate.

However, many view the movement as giving a voice to people who previously didn't have one, allowing them to call out offensive behavior for the first time.

HARPER'S LETTER

"We're no longer in a cultural moment where people who are treated unfairly can't speak back to regressive and toxic opinions," said University of Michigan professor Lisa Nakamura.

"If a public figure wants to cancel transgender people, there is no reason in the world that they can't be cancelled in return," she added.

"Cancel culture" roared into the mainstream as part of the #MeToo movement in 2017, when many Hollywood A-listers were toppled by a wave of fury over accusations of sexual harassment and abuse with impunity.

Now, the culture is impacting discriminatory behavior in everyday life, researchers say.

Nakamura cites the example of Amy Cooper, a white woman filmed by a black man in Central Park in May when she told police he was threatening her and asked them to arrest him -- for no legitimate reason.

The video, posted on Twitter, has been viewed some 45 million times amid widespread outrage, and Cooper was quickly fired as her company tried to distance itself from the anger.

"'Cancel culture' is what happens when victims of racism and sexism stop keeping their perpetrators' secrets," Nakamura told AFP.

But Keith Hampton, professor of media and information at Michigan State University, says that if the movement is intentionally about trying to harm people, then it's "less positive."

The authors of the Harper's letter warned that the radicalization of "cancel culture" was constricting the "free exchange of information and ideas."

Critics dismissed the letter as powerful people -- several of whom had been cancelled themselves after using their platforms to express controversial or offensive opinions -- complaining of backlash when people disagree with them.

Ford, at Stanford, says social media "encourages provocations and expressions of outrage and is almost completely incapable of conveying nuance."

"Sometimes the goal is simply emotional satisfaction at taking someone down," said Ford.

'US VERSUS THEM’

Hampton, from Michigan State, says "guilt and social shaming don't really change opinions very successfully," adding that that part of the movement is likely to increase the polarization of American society.

Ford says it is U.S. President Donald Trump who fueled "cancel culture" by attacking individuals and groups he wanted to discredit -- such as the Black Lives Matter movement.

"Trump's intolerance and bigotry has inspired similar behavior from his followers on the right, and that has in turn provoked a counter-reaction from progressives," said Ford.

"There's increasingly a sort of 'us versus them' attitude where it's seen as justified and even necessary to be just as dogmatic and unyielding as one's ideological enemies."

Nakamura believes the phenomenon can be problematic when it divides a social movement or "targets people inaccurately" but says, ultimately, it's "an important force for change."

"The Black Lives Matter movement would have looked very different were it not for the documentation of everyday racism in Walmarts, on jogging and bike paths, and in other public spaces," she concluded.