The death of a young woman, Mahsa Amini, in the custody of Iran's morality police in Tehran has ignited nationwide anger.
Here are some facts about the morality police, known as the Gasht e Ershad or guidance patrols, tasked with detaining people who violate Iran's conservative dress code in order to "promote virtue and prevent vice".
The morality police, attached to Iran's law enforcement, are tasked with ensuring the respect of Islamic morals as described by the country's top clerical authorities.
The typical unit consists of a van with a mixed male and female crew that patrols or waits at busy public spaces to police non-proper behaviour and dress.
People apprehended by the morality police are either given a notice or, in a few cases, taken to "correctional facilities" or a police station where they are lectured on how to dress or act morally before being released to their male relatives.
Fines are sometimes given, although there is no general rule about pecuniary punishment.
In Islam, hijab refers to what is deemed modest attire. Under Iran's sharia, or Islamic law, women are obliged to cover their hair and wear long, loose-fitting clothes to disguise their figures.
Decades after the 1979 Islamic Revolution, clerical rulers still struggle to enforce the law, with many women of all ages and backgrounds wearing tight-fitting, thigh-length coats and brightly coloured scarves pushed back to expose plenty of hair.
The morality police are often made up of and backed by the Basij, a paramilitary force initially mobilised to fight in the Iran-Iraq war in the 1980s.
Basij have a presence in every Iranian university to monitor people's dress and behaviour as higher learning is where Iranian male and females meet for the first time in a mixed educational environment.
The fight against "bad hijab" is as old as the Islamic Revolution, which has erected the conservative dressing of women as one of its pillars.
Over the revolution's early years, the state gradually imposed rules to enforce the wearing of Islamic attire by women.
Buoyed by Ayatollah Ruhollah Khomeini's claims in favour of hijab after the Shah's fall, revolutionaries took it upon themselves to enforce their leader's positions by attacking unveiled women in the streets and shouting "Woman, wear a veil or eat my hand".
Following several circulars shared by high clerics and ministers, unveiled women were no longer allowed in public buildings and the non-wearing of the veil became punishable by 74 lashes after a 1983 law.
Iran's revolutionary state struggled to control self-styled elements such as the Jundallah group patrolling streets to "combat bad hijab" and decided to institutionalise amorality police.
Under reformist President Mohammad Khatami, state fervour to control dressing and behaviour in public spaces subsided but at the end of his term in 2005, the Supreme Council of Cultural Revolution adopted the resolution named "strategies to develop a culture of chastity".
Under Khatami's successor, the ultra-conservative Mahmoud Ahmadinejad, the morality police took their current Persian name of Guidance Patrols (Gasht e Ershad) and increased their presence in the streets of Iran's large cities.
The need for a morality police was subsequently debated in the 2009 presidential elections, with reformist candidates calling for the dissolution of the force. However, no action has so far been taken to remove the morality police with many videos shared online of their sometime heavy-handed approach.