What is the Islamic ruling on torturing detainees?

In a Nutshell: Torturing the accused is a crime in Islam punishable on conviction whilst confessions extracted by torture have no value in cases. Not only this, but even if the accused is found guilty through a sound and straight judicial trial, it is not permissible for a judge to impose a penalty on the accused that involves torture. Principles of the Shari'a 1. Innocent until proven guilty Every individual is innocent until proven guilty. No one should be punished without a court sentence. Torturing is forbidden and whoever inflicts torture on anyone can be punished. The evidence for this appears in a number of ahadith. Muslim reported on the authority of Wa'il Ibnu Hajr who said: جَاءَ رَجُلٌ مِنْ حَضْرَمَوْتَ وَرَجُلٌ مِنْ كِنْدَةَ إِلَى النَّبِيِّ r، فَقَالَ الْحَضْرَمِيُّ: يَا رَسُولَ اللَّهِ، إِنَّ هَذَا قَدْ غَلَبَنِي عَلَى أَرْضٍ لِي كَانَتْ لأَبِي، فَقَالَ الْكِنْدِيُّ: هِيَ أَرْضِي فِي يَدِي أَزْرَعُهَا لَيْسَ لَهُ فِيهَا حَقٌّ، فَقَالَ رَسُولُ اللَّهِ r لِلْحَضْرَمِيِّ: أَلَكَ بَيِّنَةٌ؟ قَالَ: لاَ، قَالَ: فَلَكَ يَمِينُهُ، قَالَ: يَا رَسُولَ اللَّهِ، إِنَّ الرَّجُلَ فَاجِرٌ لا يُبَالِي عَلَى مَا حَلَفَ عَلَيْهِ وَلَيْسَ يَتَوَرَّعُ مِنْ شَيْءٍ، فَقَالَ: لَيْسَ لَكَ مِنْهُ إِلاَّ ذَلِكَ "A man from Hadhramawt and a man from Kindah came to the Messenger of Allah (saw) and the Hadhrami said: "O Messenger of Allah, this man has taken from a land which belonged to my father." The Kindi said: "It is my land, it is in my possession and I am farming it. He has no claim over it." The Messenger of Allah (saw) said to the Hadhrami: "Do you have any proof?" He said: "No." Upon this the Messenger of Allah (saw) said: "In this case you have his oath." He said: "O Messenger of Allah! He is a rebel, he does not care what he swears and he does not fear of anything." He (saw) said: "You have no other rights over him but this." (Sahih al-Muslim) Bayhaqi also related with a sahih (authentic) chain of authorities that the Prophet (saw) said: الْبَيِّنَةُ عَلَى الْمُدَّعِي ، وَالْيَمِينُ عَلَى مَنْ أَنْكَرْ "The proof lies with the plaintiff and that of the oath lies with the defendant." (Bayhaqi) In the first hadith, the Prophet (saw) commissioned the plaintiff with proof, meaning a defendant is innocent until proven guilty; in the second hadith, he (saw) explained the proof should be provided by the plaintiff. This serves as evidence that the defendant is innocent until proven guilty. 2. Torture is Forbidden The accused is innocent until proven guilty, so it is forbidden to torture him in any way to extract his confession and there are shari'a evidences that forbid doing so: a. Allah has forbidden assault against a Muslim, on his body or on any part of his body and decreed a Shari' punishment on the one who commits the assault on any of that, Allah said: وَالَّذِينَ يُؤْذُونَ الْمُؤْمِنِينَ وَالْمُؤْمِنَاتِ بِغَيْرِ مَا اكْتَسَبُوا فَقَدِ احْتَمَلُوا بُهْتَاناً وَإِثْماً مُبِيناً "And those who harm believing men and believing women for [something] other than what they have earned have certainly born upon themselves a slander and manifest sin." (Qur'an al-Ahzaab: 58) b. Muslim narrated in his Sahih from Hisham ibn Hakim ibn Hizam, He said: I heard the Messenger of Allah (saw) saying: إِنَّ اللهَ يُعَذِّبُ الَّذِينَ يُعَذِّبُونَ فِي الدُّنْيَا "Allah would torture those who torture people in this world." (Sahih al-Muslim) c. Muslim narrated in his Sahih from Abu Hurayrah said: The Messenger of Allah (saw) said: صِنْفَانِ مِنْ أَهْلِ النَّارِ لَمْ أَرَهُمَا، قَوْمٌ مَعَهُمْ سِيَاطٌ كَأَذْنَابِ الْبَقَرِ يَضْرِبُونَ بِهَا النَّاسَ... "There are two types of the people of Hell I have not seen yet: men with whips like the tails of cattle, with which they strike the people..." (Sahih al-Muslim) 3. Confessions from Torture have no value Extracting confessions under duress have no value and are not considered as they were not taken freely: - Ibn Majah reported in his Sunan on the authority of Abu Dharr al-Ghafari (ra), who said the Prophet (saw) said: إِنَّ اللَّهَ قَدْ تَجَاوَزَ عَنْ أُمَّتِي الْخَطَأَ، وَالنِّسْيَانَ، وَمَا اسْتُكْرِهُوا عَلَيْهِ Verily Allah has pardoned [or been lenient with] for me my ummah: their mistakes, their forgetfulness and that did under duress." (Ibn Majah) Whatever one is forced to do under duress is not punishable. - Al-Hakim transmitted in al-Mustadrak from the Musnads of the two imams on the authority of Ibn Abbas (ra) who said the Prophet (saw) said: تَجَاوَزَ اللَّهُ عَنْ أُمَّتِي الْخَطَأَ، وَالنِّسْيَانَ، وَمَا اسْتُكْرِهُوا عَلَيْهِ "Allah has pardoned [or been lenient with] for my ummah: their mistakes, their forgetfulness and that done under duress." (Hakim) 4. Shari'a Punishments If the charge against the accused was proven by shari'a evidences before a competent judge, it is forbidden to punish anyone by anything other than the punishments decreed by the shari'a. For example, it is forbidden to inflict a punishment which Allah (swt) has made a punishment in the Hereafter. The evidence for this is what was extracted by Bukhari on the authority of Abu Hurayrah who said, the Prophet (saw) said: وَإِنَّ النَّارَ لا يُعَذِّبُ بِهَا إِلاَّ اللَّهُ "And only Allah punishes with fire." (Abu Dawud) Therefore, if the accused were proven to be guilty before a competent judge and before a court of law, he should not be punished by fire, nor by that which is similar, such as electricity, nor by anything which Allah (swt) punishes with. Furthermore, it is forbidden to inflict any punishment from among those not decreed by the Legislator. So, no one should be punished by burning with fire, pulling out of nails or eyebrows, electrocution, drowning, pouring hot/cold water over them, starvation, leaving them to go cold, or anything similar. Punishing the accused should be confined to the penalties decreed by shari'a and apart from these, a judge is forbidden from applying any other form of punishment. Conclusion It is absolutely forbidden to torture anyone and who does so will be violating shari'a. If it is established that someone has tortured anyone else, he will be punished.