From Qur’an to Fiqh: Sunni and Shi‘i Tafsīr on the Inheritance Verses and the ‘Named Cases’ (al-Masā’il al-Mulaqqaba)

The inheritance system in force in pagan times was based on the agnatic kinship, that is the blood tie exclusively on the male line. The proximity was the basic principle of that system: the nearest male excludes the most remote. Males on the same degree inherit on an equal footing.
Qur’an includes some verses on the inheritance fixing determined shares. However, Sunni, Zahiri, Ibadi and Zaydi law schools interpreted them as a reform of the pre-Islamic customary law: firstly, shares are to be attributed to those relatives entitled to receive them; if there is anything left, the remainder shall be allotted to the agnates, according to their proximity to the deceased. On the contrary, Imami and Isma‘ili schools believe that the Qur’anic provisions constitute a break with the past; thus, the pagan principle of agnation must be rejected. The denial of the agnation highlights another peculiar rule: the principle of proximity is no longer valid for agnates only, but for all blood relatives: the next of kin among the dhawu’l-arham is entitled to inherit to the exclusion of the most remote, even if he is an agnate.
Sunni and Shi‘i tafsirs show a different reading of the Qur’anic verses on inheritance, which led to the creation of two different systems.
The Sunni tafsirs here considered are the Tafsir al-Qur’an al-karim by Sufyan al-Thawri (d. 161/777-778) and the Jami‘ al-Bayan ‘an al-Qur’an by al-Tabari (d. 310/923). The Shi‘i commentaries are the Tafsir Furat al-Kufi (d. about 310/922) and al-Tibyan fi Tafsir al-Qur’an by al-Tusi (d. 460/1067).
As a consequence of the different interpretation of the Qur’anic verses, Imamis and Isma‘ilis created a coherent and simple system based on general principles. For this, they completely ignore any case denomination. On the contrary, the remaining law schools dealt with the position of each heir, examining all possible cases involving each one. More than once they gave a special denomination to some cases. Al-masa’il al-mulaqqaba are called those legal cases denominated by special names. A typical term has the advantage of calling to mind the specific case and the debate it has provoked. They are almost exclusively present in the inheritance law. Moreover, they are generally found in later works.