Metropolitan Police officers are now required to disclose their membership of the Freemasons to their superiors.
The UK's largest force has incorporated the organisation into its declarable associations policy, placing it alongside other "hierarchical organisations."
Freemasons swear an oath of loyalty to the fraternity's principles and to supporting fellow members.
Officers and staff are now required to declare membership “past or present” of any organisation that is “hierarchical, has confidential membership and requires members to support and protect each other”, the force said.
The move was recommended by the Daniel Morgan Independent Panel report – a probe into the force’s handling of the unsolved 1987 murder of private detective Daniel Morgan.
The 37-year-old father-of-two was killed with an axe in the car park of the Golden Lion pub in Sydenham, south-east London, on March 10 1987.
A string of inquiries over the decades unearthed allegations of corruption.
The 2021 report said police officers’ membership of the Freemasons had been “a source of recurring suspicion and mistrust in the investigations”.
The Met’s decision follows a survey of officers and staff which showed two thirds of respondents felt membership of such organisations affects perception of police impartiality and public trust, the force said.
Metropolitan Police Federation general secretary Matt Cane has previously said the move could violate officers’ human rights and would be “unnecessary and wrong”.
Met Commander Simon Messinger said: “Successive leaders of the Met have considered for many years whether we need to amend our declarable association policy, particularly in relation to Freemasonry.
“After such conclusive results from our consultation, we have decided now is the right time to address long-standing concerns and that public and staff confidence must take precedence over the secrecy of any membership organisation.
“Our decision does not mean any member of staff cannot join the Freemasons or another similar organisation.
“But we have acted on feedback that involvement in these types of organisations could call impartiality into question or give rise to conflict of loyalties.
“Strengthening the trust both our own staff and London’s communities have in the Met is a core part of our New Met for London plan and ambitions.”
Senior officers have discussed the decision with the United Grand Lodge of England (UGLE) – the headquarters of Freemasonry in England and Wales, the Met said.
But responding to the decision, UGLE said there had not been a genuine dialogue.
A spokesperson said the move was “unlawful, disproportionate, unfair and discriminatory”.
Commenting on behalf of UGLE, the Order of Women Freemasons and the Honourable Fraternity of Ancient Freemasons, Adrian Marsh said: “We are disappointed that a decision which potentially affects our members has been taken without open or effective consultation.
“Our values of integrity, friendship, respect and service are paramount in Freemasonry and have never been of more importance.
“We see this action as unwarranted, and we are carefully considering an appropriate response. We will issue a further statement in due course.”
Frozen pangolin among illegal bushmeat seized in capital
Tanzanian cities are empty as police patrol streets following calls for protests
Heartbroken sister issues urgent warning to Christmas shoppers after e-bike tragedy
‘The last time my son was seen he stepped on a train. He was never heard from again’
Flu cases in NHS hospitals jump 55% in one week, figures show
