ISIS has issued an extremely detailed ruling on when the 'owners' of female slaves can have sex with them in a sickening attempt to justify the rape and torture of its captives.
The ruling or fatwa has the force of law and appears to go beyond ISIS's previous known utterances on the subject, a leading Islamic State scholar said.
It sheds new light on how the group is trying to reinterpret centuries-old teachings to sanction the sexual slavery of women in the swaths of Syria and Iraq it controls.
The fatwa was among a huge trove of documents captured by U.S. Special Operations Forces during a raid targeting a top ISIS official in Syria in May.
Reuters news agency has reviewed some of the documents, which have not been previously published.
Among the religious rulings are bans on a father and son having sex with the same female slave; and the owner of a mother and daughter having sex with both.
Joint owners of a female captive are similarly enjoined from intercourse because she is viewed as 'part of a joint ownership.'
The United Nations and human rights groups have accused ISIS of the systematic abduction and rape of thousands of women and girls as young as 12, especially members of the Yazidi minority in northern Iraq.
Many have been given to fighters as a reward or sold as sex slaves.
Far from trying to conceal the practice, Islamic State has boasted about it and established a department of 'war spoils' to manage slavery.
Reuters reported on the existence of the department on Monday.
In an April report, Human Rights Watch interviewed 20 female escapees who recounted how Islamic State fighters separated young women and girls from men and boys and older women.
They were moved 'in an organized and methodical fashion to various places in Iraq and Syria.'
They were then sold or given as gifts and repeatedly raped or subjected to sexual violence.
Fatwa No. 64, dated January 29, 2015, and issued by the terror group's Committee of Research and Fatwas, appears to codify sexual relations between ISIS fighters and their female captives for the first time, going further than a pamphlet issued by the group in 2014 on how to treat slaves.
The fatwa starts with a question: 'Some of the brothers have committed violations in the matter of the treatment of the female slaves.
'These violations are not permitted by Sharia law because these rules have not been dealt with in ages. Are there any warnings pertaining to this matter?'
It then lists 15 injunctions, which in some instances go into explicit detail.
For example, one says: 'If the owner of a female captive, who has a daughter suitable for intercourse, has sexual relations with the latter, he is not permitted to have intercourse with her mother and she is permanently off limits to him.
'Should he have intercourse with her mother then he is not permitted to have intercourse with her daughter and she is to be off limits to him.'
ISIS's sexual exploitation of female captives has been well documented, but a leading ISIS expert at Princeton University, Cole Bunzel, who has reviewed many of the group's writings, said the fatwa went beyond what has previously been published by the militants on how to treat female slaves.
'It reveals the actual concerns of ISIS slave owners,' he said in an email.
Still, he cautioned that not 'everything dealt with in the fatwa is indicative of a relevant violation.
'It doesn't mean father and son were necessarily sharing a girl. They're at least being 'warned' not to. But I bet some of these violations were being committed.'
The fatwa also instructs owners of female slaves to 'show compassion towards her, be kind to her, not humiliate her and not assign her work she is unable to perform.'
An owner should also not sell her to an individual whom he knows will mistreat her.
Professor Abdel Fattah Alawari, dean of Islamic Theology at Al-Azhar University, a 1,000-year-old Egyptian centre for Islamic learning, said ISIS 'has nothing to do with Islam' and was deliberately misreading centuries-old verses and sayings that were originally designed to end, rather than encourage, slavery.
'Islam preaches freedom to slaves, not slavery. Slavery was the status quo when Islam came around,' he said.
'Judaism, Christianity, Greek, Roman and Persian civilisations all practiced it and took the females of their enemies as sex slaves.
'So Islam found this abhorrent practice and worked to gradually remove it.'
In September 2014, more than 120 Islamic scholars from around the world issued an open letter to ISIS leader Abu Bakr al-Baghdadi refuting the group's religious arguments to justify many of its actions.
The scholars noted that the 'reintroduction of slavery is forbidden in Islam.'
THE 15 DOS AND DON'TS FOR 'OWNERS' OF ISIS FEMALE SEX SLAVES
It is not permissible for the owner of a female captive to have intercourse with her until after she has had menstrual cycle and becomes clean.
If she does not menstruate and is pregnant, he is not allowed to have intercourse with her until after she has given birth.
It is not permissible to cause her to abort if she is pregnant.
If the owner of a female captive releases her, only he can have intercourse with her and he cannot allow someone else to have intercourse with her.
If the owner of a female captive, who has a daughter suitable for intercourse, has sexual relations with the latter, he is not permitted to have intercourse with her mother and she is permanently off limits to him. Should he have intercourse with her mother then he is not permitted to have intercourse with her daughter and she is to be off-limits to him.
The owner of two sisters is not allowed to have intercourse with both of them; rather he may only have intercourse with just one. The other sister is to be had by him, if he were to relinquish ownership of the first sister by selling her, giving her away or releasing her
If the female captive is owned by a father, his son cannot have intercourse with her and vice-versa. Moreover, intercourse with his wife's female captive is also not permissible
If a father had intercourse with his female captive then gave her away or sold her to his son, he is no longer permitted to have intercourse with her
If the female captive becomes pregnant by her owner, he cannot sell her and she is released after his death
If the owner releases his female captive then he is not permitted to have intercourse with her afterwards because she has become free and is no longer his property
If two or more individuals are involved in purchasing a female captive, none of them are permitted to have sex with her because she is part of a joint ownership
It is not permissible to have intercouse with a female captive during her menstrual cycle
It is not permissible top have anal sex with a female captive
The owner of a female captive should show compassion towards her, be kind to her, not humiliate her and not assign her work she is unable to perform
The owner of a female captive should not sell her to an individual whom he knows will treat her badly or do unto her what Allah has forbidden