There is a renewed interest in translating classical texts about Islamic rules of war into English, adding to the increasing body of work on the intersections between Islam, international humanitarian law (IHL) and the protection of civilians. IRIN provides this study guide to get you started.
Majid Khadduri’s translation (with explanation) of the Islamic Law of Nations, the first codification of Islamic rules of war by jurist Mohammad Ibn al-Hassan al-Shaybani, is a good place to start.
Sahih Muslim is one of the main references for authenticated hadiths, or sayings of the Prophet Muhammad, one of the sources of Islamic law. Here is a translation of those hadiths that address jihad and military expeditions.
Yusuf Qaradawi’s Fiqh al-Jihad (the Jurisprudence of War) is another foundational text giving modern interpretations of the Islamic laws of war from a conservative perspective. The book itself is not online, but you can find reviews.
Khaled Abou El Fadl, of the University of California, Los Angeles, is one of the leading academics studying Islamic laws of war. You can find his reading of the classical sources in this 1999 article in The Muslim World.
But there are a plethora of other academics studying the humanitarian provisions in Islamic rules of war. Among them: Nesrine Badawi at the American University in Cairo; Mohammad Fadel at the University of Toronto; Muhammad Munir at the International Islamic University in Islamabad; Andrew March at Yale University; and Joel Hayward of Khalifa University in Abu Dhabi.
The reading list for the Islamic Law and the Protection of Civilians workshop offered by Professionals in Humanitarian Assistance and Protection (PHAP) is an excellent resource with plenty of references, from primary sources to jihadi doctrine and analysis.
It includes this web seminar from the Program on Humanitarian Policy and Conflict Research at Harvard University, which gives a good overview of the issues raised in our series.
Similarly, you’ll find a whole series of articles on this forum at Syracuse University, which has an initiative on Islam and IHL.
There are endless studies on the subject, including this examination by Malaysian professors of what constitutes Direct Participation in Hostilities (DPH) in the Islamic context and this article by Mohamed Elewa Badar analyzing the role of Islam in shaping modern European laws of war
Harvard lawyer Naz Modirzadeh has published a number of journal articles on the practical relevance of all this for humanitarian and human rights practitioners. This one in the Harvard Human Rights Journal critiques international NGOs for failing to truly engage with Islamic law; while the final segment of this one in the European Journal of International Law delves into why there is so much interest in Islamic law and war.
For more on militant interpretations and application of Islamic law, the Geneva Academy of International Humanitarian Law and Human rights recently published a policy brief rife with examples and insights into Islamist armed groups’ behaviour. A 2010 essay by Human Rights Watch’s Joe Stork is another window into some of the intra-Islamist debate on acceptable behavior in times of war.
Finally, this handbook to refuting jihadism by the Henry Jackson Society is a fascinating attempt to challenge the theological authenticity of militant arguments.