Pc Gurmeal Singh was ordered to remove his turban for riot training
Sikh police officers who wear turbans cannot join firearms teams, following a ruling from the Association of Chief Police Officers (Acpo).
Officers can choose instead to wear a smaller head covering known as a patka, which will fit under a helmet.
The Acpo guidance follows consultations with the Home Office and a range of police associations representing Sikhs.
In 2009, a tribunal awarded £10,000 to a Sikh officer who was ordered to remove his turban during riot training.
The British Sikh Police Association asked for a clarification from Acpo following the award, and proposed a "ballistic turban" that would provide head protection.
Acpo opted against the ballistic turban approach but said the idea was worth "future exploration".
"The police service has a legal duty to consider the health and safety of staff at work and provide appropriate personal protective equipment to staff who are placed in high risk situations," said Chief Constable Meredydd Hughes, Acpo's head of uniformed operations.
As a result, Sikh officers will only be permitted to engage in armed operations if they remove their turbans or wear the smaller patka head covering to permit the use of a helmet for protection.
Chief Constable Hughes said that wearing a patka was "a matter of choice for the police officer", adding that "Sikh officers who wear a turban will not be discriminated against if they choose not to perform firearms or higher-level public order duties".
'Treated with fairness'
Gurpal Virdi, office co-ordinator for the Metropolitan Police Sikh Association, welcomed the clarification.
"Supervising officers had no idea how to deal with Sikh officers before; there was no guidance," he told BBC News.
"Some Sikh officers were being discriminated against, especially in rural constabularies.
"The guidance now makes clear how Sikh officers should be treated with fairness."