It is a 365-year-old institution revered the world over, with past members including luminaries such as Isaac Newton, Charles Darwin and Dorothy Hodgkin. But now a row over a billionaire maverick has thrown the Royal Society into crisis, splintering the fellowship and raising existential questions about its role in society.

A growing number of scientists have called for the academy to investigate the conduct of Elon Musk – who was elected a fellow in 2018 – resulting in a passionate debate at a meeting of the scientific body on Monday evening.

Critics claim Musk’s behaviour has violated the Royal Society’s code, citing his incendiary comments about British politicians, his calls for the American doctor and scientist Anthony Fauci to be prosecuted, and his role in slashing research funding through his work with the so-called US “department of government efficiency” (Doge) – among other acts.

Several fellows have even called openly for Musk to be ejected from the academy.

“I think Elon Musk should be expelled from the British Royal Society,” the Nobel laureate and AI pioneer Geoffrey Hinton wrote on X. “Not because he peddles conspiracy theories and makes Nazi salutes, but because of the huge damage he is doing to scientific institutions in the US. Now let’s see if he really believes in free speech.”

Musk replied: “Only craven, insecure fools care about awards and memberships. History is the actual judge, always and forever. Your comments above are carelessly ignorant, cruel and false. That said, what specific actions require correction? I will make mistakes, but endeavor to fix them fast.”

Perhaps it is just such a volte-face the Royal Society is banking on. Because despite private communications, an open letter signed by more than 3,500 members of the scientific community, resignations by fellows and journal editors and Monday’s meeting, the academy has yet to comment on the tech entrepreneur.

While Musk’s behaviour is very public, the Royal Society insists its handling of concerns remains confidential. Fellows have been instructed not to talk to the press while the academy itself has released only a broad statement after Monday’s meeting outlining fellows’ concerns about cuts to research funding in the US and the need for the society to step up its efforts to advocate for science and scientists.

“The society agreed to look at potential further actions that might help make the case for science and scientific research and counter the misinformation and ideologically motivated attacks on both science and scientists,” the statement added.

What form that might take is unclear. The Guardian understands a letter will be sent to Musk from the Royal Society (although its contents have yet to be decided) and – at present – no formal proceedings or investigations are under way.

It is not the first time Musk has divided opinions among the fellowship. Not everyone was happy when he was proposed for election – an honour apparently bestowed for his work in fields including space travel and sustainable electric transportation.

Becoming a fellow of the Royal Society is often seen as the pinnacle of a long research career. But Musk is a businessman, not an academic, and some argue that he is not himself an innovator.

At the heart of the latest furore is whether Musk has violated the academy’s code of conduct, which includes the stipulation that fellows shall “not act or fail to act in any way which would undermine the Society’s mission or bring the Society into disrepute”.

“I haven’t yet come across anybody who has made a clear argument that actually Elon Musk is not in contravention of the code of conduct,” said Stephen Curry, an emeritus professor of structural biology at Imperial College London, who – while not a fellow – wrote the open letter many fellows signed.

Curry said rebuttals had focused on concerns about punishing people for their political views. “But I reject that completely,” he said.

Prof Dorothy Bishop, a leading expert on children’s communication disorders, revealed that after she and other fellows initially raised concerns about Musk’s behaviour in the summer of 2024 and a lawyer for the academy determined Musk had not breached the code. The group subsequently set about gathering further evidence of breaches but for Bishop the situation became untenable. She resigned her fellowship in November.

In February, another fellow, Prof Andrew Millar, followed suit.

The Royal Society’s documents set out that if an investigation into allegations of misconduct is upheld, the matter would pass to the conduct committee, a hearing would take place, and – if misconduct is deemed to have occurred – sanctions would be applied, with expulsion among the options.

Yet Bishop said no fellow has been ejected from the academy in more than 150 years.

“It does suggest that the statutes are worded so that it is virtually impossible to do anything about fellows who breach the code of conduct,” she wrote in her resignation statement.

One of the few fellows to be ejected was Rudolf Erich Raspe, who was booted out in 1775 after being charged with “divers frauds and gross breaches of trust”.

Expelling Musk might bring new headaches, not least as he is not the only controversial fellow. In inviting fellows to Monday’s meeting, the academy’s president, Sir Adrian Smith,said: “The business of the society is the advancement of the cause of science through rigorous rational scientific debate and council considers that we are on difficult ground if the society makes judgments as to the acceptability of the views or affiliations of our colleagues.”

Expelling Musk could also be politically difficult at a time of heightened tensions between the UK and US. Some in the scientific community are adamant science should not be politicised, and have argued revoking Musk’s fellowship could undermine trust in science.

“In a nutshell, my argument is that the public trusts scientists more than politicians because it believes they are impartial and objective experts. Scientists who stray beyond the evidence and become campaigners or advocates for particular policies risk losing that trust,” Fiona Fox, a fellow of the Royal Society and chief executive of the Science Media Centre, wrote. “My worry is that ejecting Musk from the Royal Society would be seen as a political move.”

Other scientists who have voiced support for Musk have argued that, despite his actions being reprehensible, Musk has made huge contributions to engineering.

At present, the Royal Society insists “any issues raised in respect of individual fellows are dealt with in strict confidence”. But some fellows back public action suggesting that, regardless of whether they launch an investigation – something that is required to be confidential under the organisation’s rules – the Royal Society should release an open letter or public statement condemning Musk’s attack on science.

Fundamentally, it seems, the Royal Society must decide, and explain, where its red lines lie – not only in theory, but in practice.