Incredible!
[snip]
When Islam came and prospered, its power was challenged by the enemies of Islam and the need to go to war arose. By that time, slavery had virtually become an international custom. It was also rife among the Arabs from the days of darkness and ignorance. Thus, abolishing it instantateously would have caused chaos and pandemonium among the Arab people. Hence, a process of gradual extirpation had to be implemented. Moreover, if the Muslims would set all their enemy-prisoners free and tolerate their fellow Muslims being captured and enslaved by the enemies, it would have lead to a sharp decrease in the Muslim military force and given a great advantage to the enemy forces which was something that the Muslims could not afford. Furthermore, it is a well known fact that warfare tactics used by one side are often countered by the opposing side in order to maintain a balance of power. Hence, wartime diplomacy necessitated the enslaving of prisoners.
In the “Jihaads” (Islamic wars) that took place, women were also, at times, taken as prisoners of war by the Muslim warriors. These women captives used to be distributed as part of the booty among the soldiers, after their return to Islamic territory. Each soldier was then entitled to have relations ONLY with the slave girl over which he was given the RIGHT OF OWNERSHIP and NOT with those slave girls that were not in his possession. This RIGHT OF OWNERSHIP was given to him by the “Ameerul-Mu'mineen” (Head of the Islamic state.) Due to this right of ownership, It became lawful for the owner of a slave girl to have intercourse with her.
It may, superficially, appear distasteful to copulate with a woman who is not a man's legal wife, but once Shariat makes something lawful, we have to accept it as lawful, whether it appeals to our taste, or not; and whether we know its underlying wisdom or not. It is necessary for a Muslim to be acquainted with the laws of Shariat, but it is not necessary for him to delve into each law in order to find the underlying wisdom of these laws because knowledge of the wisdom of some of the laws may be beyond his puny comprehension. Allah Ta'ala has said in the Holy Quran: “Wa maa ooteetum min al-ilm illaa qaleelan” which means, more or less, that, "You have been given a very small portion of knowledge”. Hence, if a person fails to comprehend the underlying wisdom of any law of Shariat, he cannot regard it as a fault of Shariat (Allah forbid), on the contrary, it is the fault of his own perception and lack of understanding, because no law of Shariat is contradictory to wisdom.
Nevertheless, the wisdom underlying the permission granted by Shariat to copulate with a slave woman is as follows: The LEGAL possession that a Muslim receives over a slave woman from the “Ameerul-Mu'mineen” (the Islamic Head of State) gives him legal credence to have coition with the slave woman in his possession, just as the marriage ceremony gives him legal credence to have coition with his wife. In other words, this LEGAL POSSESSION is, in effect, a SUBSTITUTE of the MARRIAGE CEREMONY. A free woman cannot be 'possessed', bought or sold like other possessions; therefore Shariat instituted a 'marriage ceremony' in which affirmation and consent takes place, which gives a man the right to copulate with her. On the other hand, a slave girl can be possessed and even bought and sold, thus, this right of possession, substituting as a marriage ceremony, entitles the owner to copulate with her. A similar example can be found in the slaughtering of animals; that after a formal slaughtering process, in which the words, “Bismillahi Allahu Akbar” are recited, goats, cows, etc.; become “Halaal” and lawful for consumption, whereas fish becomes “Halaal” merely through 'possession' which substitutes for the slaughtering.
In other words, just as legal possession of a fish that has been fished out of the water, makes it Halaal for human consumption without the initiation of a formal slaughtering process; similarly legal possession of a slave woman made her Halaal for the purpose of coition with her owner without the initiation of a formal marriage ceremony.
In short, permission to have intercourse with a slave woman was not something barbaric or uncivilised; on the contrary, it was almost as good as a marriage ceremony. In fact, possession of a slave woman resembles a marriage ceremony in many ways and both have a lot in common with each other. One similarity is this that just as a free woman cannot have two husbands simultaneously, a slave woman cannot be used for intercourse by two owners. Another similarity is that a free woman whose marriage is on the rocks, cannot marry another man until her previous marriage is nullified through divorce, etc. Due to the discrepancies between husband and wife, the marriage sometimes reaches a stage where it becomes virtually impossible for the couple to live as man and wife with the result that divorce is brought into force to nullify marriage ties. Similarly, if a slave woman was married previously in enemy territory to a non-Muslim, and is then captured alone, i.e. without her husband, it is not permissible for any Muslim to have relations with her until her previous marriage is nullified, and that is done by bringing her to an Islamic country and making her the legal possession of a Muslim. Bringing her into Islamic territory necessitates the rendering of her previous marriage as null and void by Islamic law because with her husband in enemy territory and she in Islamic territory, it becomes virtually impossible for them to meet and live as man and wife. That is why it is not permissible to have intercourse with a woman whose husband is also taken into captivity and put into slavery with her. Another resemblance between the two is that, just as a divorcee has to spend a period called "Iddat" before another man is allowed to marry her, similarly, a slave woman has to spend a period called "Istibraa" before her owner can have coition with her.
Another similarity between marriage and possession of a slave woman is that just as the wife becomes a dependant of the husband and he has to provide a home, food and clothing for her, a slave woman also becomes a dependant of her owner and he has to provide a home, food and clothing for her. Yet another similarity is this that just as marriage makes the close relatives of the wife Haraam upon the husband; i.e. he cannot get married to his wife's mother, grandmother, sister, etc., similarly if a man has copulated with a slave woman the slave woman's close relatives also become Haraam upon the owner. With all these similarities it does not make sense to regard copulation with a slave woman distasteful whilst copulation with one's wife is not regarded as distasteful.
A question that may still arise is that why does the owner of a slave woman not marry her before having relations with her? Well, this is impracticable because of a few intricate technicalities. Firstly, we know that a man has to give “Mahr” (dower-money) to his bride.
[snip]
Thus, “Mahr” is a conditional prerequisite of Nikah. If a man has to marry his slave woman, it would not be possible for him to abide by this condition of 'Mahr' because by Islamic law, a slave does not have rights over any property, i.e. she cannot own anything. In fact, whatever she has with her too, i.e. her clothing, etc., is all regarded as the property of her owner. Therefore, If he gets married to his slave girl and gives her the 'Mahr' she cannot become the owner of it because she has no right of ownership. The 'Mahr' would bounce back to the owner of the slave girl and it would tantamount to giving the 'mahr' to himself. Hence, the owner would become the payer as well as the PAYEE of the 'mahr' which would only result in the mockery of the whole system of 'mahr'. It would be absolutely superflous to have such a marriage ceremony performed that makes a mockery of the 'mahr' system. Hence, the owner cannot get married to her while she remains a slave girl. However, if he sets her free, then he can get married to her on the basis of her having become a liberated woman.
Although the owner himself cannot get married to his slave woman, without giving her freedom, he can get her married to someone else. If he gets her married to someone else, then only her husband can now have intercourse with her and the owner's right of having intercourse with her comes to an end. All these facts prove that the slave girl does not become an instrument of sex; on the contrary, her honour is upheld, in that only one man is allowed to have intercourse with her JUST AS only one man (the husband) is allowed to have intercourse with his lawfully wedded wife.
Islam ensured that the slave girl's duties were not restricted merely to domestic chores but also gave her master permission to copulate with her. This concession created an atmosphere of love and harmony between the slave girl and her master. Islam thereby raised the status of the war captive-maidens close to that of wives. It was a psychological cure to her grief-stricken heart, being deprived of her family and thrown into the hands of a strange society.
Rasulullah (Sallallahu Alayhi Wasallam) enjoined his followers to treat the slaves kindly, gently, and, above all, to regard them as members of the family. In this way, they were made to feel wanted; which was far better than treating them as outcasts and leaving them to wander the streets of a strange society in a peniless, destitute condition. Such treatment would have ultimately forced them to take up evil occupations such as prostitution in the case of slave woman in order to fill their hungry stomachs. The First World War in 1914 was a clear reflection of the evils involved in setting captive women free to roars about in a strange society with strange surroundings. During that war, German and English women prisoners on either side were set free to roam the streets with no-one to feed them. The result was obvious that they resorted to other unrefined and uncivilised methods of income on the streets. Thus, it is evident that the Islamic treatment of women prisoners of war was conducive towards better social relations and led to the refinement of their overall social lives
[snip]
One question that still remains is whether slavery still legally prevails anywhere in the Islamic world and whether it can be successfully implemented in this age. Well, there is no prevalence of lawful slavery in the Islamic world today and it would be difficult to implement it because of the stringent conditions attached to it. Firstly, the prisoners have to be captured in 'Jihaad' in the true sense of the word. Then again, If true 'Jihaad' did break out somewhere, there are still a number of other laws and conditions to abide by which are far too stringent for any Islamic country in the world to abide by in this time and age when people's personal gains and whims and desire are being given preference to over Islamic Law. According to Islamic Law, captive female prisoners are also part and parcel of the booty. One fifth of the booty has to be first distributed to the needy, orphans, etc. The remaining four-fifths should then be distributed among the soldiers who participated in the war. The distribution can only take effect after the booty is brought into Islamic territory. The Ameerul-Mu'mineen (Head of the Islamic State) remains the guardian of the female prisoners until he allocates them to the soldiers. Only after a soldier has been allotted a slave girl, and made the owner of her, will she become his lawful possession. After she spends a period called 'Istibraa', which is the elapse of one menstrual period, It becomes permissible for her owner to have relations with her. After possession of the slave too there are a number of other laws that affect the master and slave. There is hardly any Islamic country today that can abide to all these conditions, with the result that it is quite difficult to implement slavery in this time and age. [snip]
He never does discuss the detail that the women DO NOT CHOOSE SLAVERY OR CONSENT TO SEXUAL ACTIVITY. It is rape.
As to whether slavery is still "legal" under Islam? Yes. There is no change to Islamic Law, the Koran defines it, thus it is okay. There will never be a reformation of Islam.
If the left would look at the language of this answer, "Jihad" does not mean "personal struggle", it is a holy war. Also if there appears to be an "us and them" mentality, the left needs to examine the concept of what a "muslim territory" is.
Christians, Jews, Buddists, Hindus, et al can only co-exist peacefully with muslims if they can CO-EXIST with other religions. This means that the law cannot distinguish between muslims, Jews/Christians, and "everybody else". It also means that free exercise of and conversion to other faiths must be tolerated.