Ibn Hazm's dhahihiri madh-hab does not represent ahl as-sunnah. Ustadh Tripoly: I'm not sure if Imam Ja'far had a madh-hab in the sense of the 4 madha-hib. Rather, he had his own ijtihaadiyyaat in various shar'i matters, just like the rest of the a'immah of the salaf did. In fact, there wasn't a uniform method of ijtihad i.e. usul used by the Ahl al-Bayt; it is quite possible that Imam 'Ali Zayn al-'abidin and Imam Ja'far would have different opinions on a single matter. However, these opinions were not autentically preserved by a group of loyal students, unlike Imam Abu Hanfifah, for example, who had Imam Abu Yusuf and Imam Muhammad (the latter compiled the dhahir ar-riwaayah for us hanafis). This is why their madha-hib did not survive. An interesting feature of the hanafi madh-hab is that it was largely based on the ijtihaad of sayyiduna 'AbduLlah b. Mas'ud, but also sayyiduna 'Ali radhiy Allah 'anhumaa, owing to its birth in the city of Kufa. was-salam