In the name of Allah, the Most Gracious, the Most Merciful. And may His perpetual peace and blessings be upon our Beloved, our Liege Muḥammad, the Chosen One.
The Earliest Forms of Law
The origins of legal theory are traced back to the emergence of law, for in making any law and jurisprudence, a modus operandi is required which is the foundation of that law. Law is traced back to the creation of Ādam (peace be upon him), and amongst the preliminary laws was Allah’s command to abstain from the tree as He says: “O Ādam! Dwell, you and your wife, in Paradise; and eat at pleasure thereof where you will, but do not approach this tree, lest you be of the wrong-doers.” (Qurʾān 2:35). Legislation perpetually continued therefrom and metamorphosed in its various forms and shapes in a multitude of traditions and communities.
In the Islamic Canon, numerous incidents connote the existence of jurisprudence in the Abrahamic faiths, namely in the Canonic codices (ṣaḥāʾif) of Ibrāhīm (peace and blessings be upon him), Judaism, the Davidic and Solomonic law, and Christianity. Archeologically, one of the oldest written bodies of laws although it is implicit itself of the existence of even earlier laws, is that of Hammurabi, king of the Babylonian empire. It is estimated to be from 1760 BCE and contains 282 laws (it is currently in the Louvre in Paris). In Western legal tradition, the emergence of law can be traced to one of the Seven Wise Men, the statesman Solon from the 6th century BCE. Later, in 450 BCE, the Romans formed a compilation of laws known as the Twelve Tables that would be binding on all Romans, the patricians and the plebeians. As Roman law evolved throughout the centuries, Justinian, the Eastern emperor commanded the codification of the Roman legal texts, introducing the Corpus Juris Civilis, inclusive of the Digest, Codex, and Institutes. After the fall of the Roman Empire, Western legal tradition came to a halt to be resumed only after centuries. It later evolved to be the more brief Napoleonic code in 1804, which played a noticeable role in the make of codified civil law.
Law and Legal Theory in the Prophetic Era
One of the most extensive and meticulous corpuses of law in history, albeit at times labyrinthine, is Islamic law. The agglomeration of literature that exists in Islamic jurisprudence and its derivatives that comprise of the law in different schools of hermeneutics, legal theory (uṣūl al-fiqh), maxims (qawāʿid), philosophy of law (maqāṣid al-sharīʿah), collections of legal responsa (fatāwā) perplexes the researcher as much as it draws him nearer.
Legal theory (uṣūl al-fiqh) was nascent in the era of the Apostle of Allah as he was a capable jurist (mujtahid) and in numerous occasions where direct Divine Revelation (waḥy) did not descend, he applied juristic reasoning (ijtihād). After the battle of Badr, the Messenger of Allah decided after deliberating and seeking the counsel of Abū Bakr and ʿUmar (may Allah be pleased with them) to free the prisoners of war in exchange for educational services. This was his juristic reasoning after deliberation, although the judgement was altered by Divine Decree. This incident is reported by Ibn ʿAbbās and Anas ibn Mālik (may Allah be pleased with them). The Beloved Prophet of Allah likewise established certain principles in jurisprudence as stated by al-Zarkashī, which are visible in all schools of legal interpretation such as the evidentiary authority of communal consensus (ijmāʿ). He said “Verily, Allah will not cause my people (ummah) to congrue on falsehood and misguidance” and an array of similar statements promoting consensus. He also established the authority of correlational inference (qiyās). In one instance, in the catechism between the Companion ʿUmar and the Messenger of Allah where the former says as reported by Jābir (may Allah be pleased with them): “I was elated [at the sight of my wife] so I kissed in a fasting state, so I said ‘O Prophet of Allah! Today, I have engaged in a great (sacrilegious) deed; I kissed while I was fasting.’ He replied: ‘What do you think of [a case] where you had rinsed your mouth with water while you were fasting?’ [ʿUmar] replied: ‘There is no harm in it.’ He said: ‘Then what do you think of this (i.e. kissing)?’”
Numerous Companions were also taught legal theory and methodology. It is narrated from multiple disciples of the Companion Muʿādh ibn Jabal in Ḥimṣ that when the Messenger of Allah intended to dispatch him to Yemen, he asked: “How will you judge when the occasion of deciding a case arises?” He said: “I shall judge in accordance with the Book of Allah.” He inquired: “And if you do not find it in the Book of Allah?” He replied: “[I shall act] in accordance with the sunnah of the Messenger of Allah (peace be upon him)” He asked: “And if you do not find it in the sunnah of the Messenger of Allah, nor in the Book of Allah?” He replied: “I shall exert myself to formulate a dialectical-juristic opinion (al-raʾy).” Thereafter the Messenger of Allah patted him on his chest saying: “All praise is due to Allah who syncretized the messenger of His messenger to what pleases His messenger.” This narration explicitly illustrates the juristic capabilities Muʿādh ibn Jabal (may Allah be pleased with him) possessed due to his prior training. Many other Companions were educated and disciplined in jurisprudence and engaged in legal responsa (fatwā) like Abū Bakr, ʿUmar, ʿUthmān, ʿAlī, ʿAbdullāh ibn Masʿūd, Abdullāh ibn ʿAbbās, Abdullāh ibn ʿUmar, Abū al-Dardāʾ, Ubayy ibn Kaʿb, Zayd ibn Thābit, ʿĀʾishah bint Abī Bakr, and many others (may Allah be pleased with all of them). They were acquainted with the legal notions of sequence in evidentiary authority (marātib al-adillah), reconciliation (tawfīq), preference of evidence (tarjīḥ), abrogation (naskh), consensus (ijmāʿ), analogy (qiyās), extrapolation of the ratio legis (ʿillah) in Canonical rulings and its application. This is apparent in their various decisions and responses when inquired concerning legal cases.
Juristic and Legal Training in Post-Prophetic Era
The Companions likewise edified and educated the Successors (tābiʿūn) in this field, transmitting and imparting their knowledge. In the era of the Successors, one of the prominent nascent principles was the reliability of the loose report (al-ḥadīth al-mursal). The doyen of Canonic exegesis Ibn Jarīr al-Ṭabarī states: “People were continually acting upon the loose report and accepting it, until its rejection was voiced after the second century.”
The Expansion of Legal Theory by Abū Ḥanīfah and His Legal School
Amongst the Successors was the jurist Abū Ḥanīfah, proficient in Canonic studies and paramount in dialectical sciences (ʿilm al-kalām), he was a beacon many behemoths of ḥadīth and jurisprudence altered the direction of their conveyances towards, including the likes of Dāwūd al-Ṭāʾī (d. 160 AH), ʿAbdullah ibn al-Mubārak (d. 181 AH), Fuḍayl ibn ʿIyāḍ (d. 187 AH), Wakīʿ ibn al-Jarrāḥ (d. 197 AH), Yaḥyā ibn Saʿīd al-Qaṭṭān (d. 198 AH), the prominent transmitters from whom Imām al-Bukhārī narrates his triadic narrations (thulāthiyyāt) from; Khallād ibn Yaḥyā (d. 213), Makkī ibn Ibrāhīm and Abū ʿĀṣim al-Nabīl (both d. 215), and over 110 others of al-Bukhārī’s teachers. He laid the foundation for multiple principles and maxims employed in jurisprudence, which are dispersed primarily in the catechisms of his disciple Muḥammad ibn al-Ḥasan. Amongst them was his scrupulousness in narrating and accepting hadith; he had made it a prerequisite for the soundness (siḥḥah) of a ḥadīth that the narrator remembers the ḥadīth from the time he hears it until he narrates it, which was the reason for the small amount of aḥādīth he narrated, despite his encompassment of innumerable aḥādīth. This prerequisite of his is reported by Ibn Abī al-ʿAwwām, al-Ḥākim al-Nīsāpūrī, the Andalusian scholar Ibn ʿAbd al-Barr, and al-Khaṭīb al-Baghdādī. He furthermore had a hand in certain principles of accrediting and discrediting (al-jarḥ wa al-taʿdīl) as he was the first to discredit Jābir al-Juʿfī the forger and the narrations of Abū Isḥāq from al-Ḥārith al-Aʿwar, as reported by Imām al-Tirmidhī in his Kitāb al-ʿilal al-saghīr, Hāfiẓ al-Dhahabī, Hāfiẓ al-Sakhāwī, al-Bayhaqī, and others.
He was the inaugurator of one of the prominent schools of legal hermeneutics in Islam, the Ḥanafite school. It originated from the juristic school of our liege ʿAbdullah ibn Masʿūd (may Allah be pleased with him) in the vibrant city of Kūfah, the nucleus of academia at the time. Amongst the disciples of the Imām was Abū Yūsuf Yaqʿūb ibn Ibrāhīm al-Anṣārī (d. 182). Despite being a highly capable and perspicacious jurist himself, he remained in the company of the Imām for a lengthy period of time, subsequently becoming the first to lay down the foundations of Islamic legal theory in writing. Although his written work in legal theory was lost to the vicissitudes of time, many historians recorded the existence of his work. The historian al-Khaṭīb al-Baghdādī relates from Talḥah ibn Muḥammad ibn Jaʿfar: “Abū Yūsuf… was the first to lay down in writing the principles of jurisprudence in the school of Abū Ḥanīfah.” This is also related by the historians al-Samʿānī and Ibn Khallakān.
The Progressive Codification of Legal Theory
A few decades later, Imām al-Shāfiʿī authored the first book in Islamic legal theory that is available today for the reader, titled al-Risālah (The Treatise). He had initially written one in Iraq, albeit later as he travelled to the metropolis of Cairo and interacted and intermingled with the variety of scholars there, such as the students of Mālik and al-Awzāʿī, he wrote a newer updated version of the older treatise. From there, the chain of compiling in the science of legal theory started and continues until today, be it in the form of corpuses or compendia, commentaries (sharḥ) or marginalia (ḥāshiyah), addenda (mustadrak or takmīl) or abridgements (mukhtaṣar). If one were to enumerate the literature in the science of legal theory, it would facilely be in the hundreds.
 Canon in this paper refers to the Qurʾān and the corpus of ḥadīth.
 See for a more extensive discussion Wacks, Raymond, Law; A Very Short Introduction, (Oxford: Oxford University Press, 2008).
 This is the opinion of mainstream scholars such as the jurists Abū Ḥanīfah, Mālik, al-Shāfiʿī, Aḥmad ibn Ḥambal, the scholars of Ḥadīth, etc. It is also the preferred view in the Ḥanafite school of legal thought. See Abū al-Ḥāj, Salāḥ, Masār al-wuṣūl ilā ʿilm al-uṣūl, (Amman: Dār al-Fatḥ, 2017), 25.
 See Qurʾān 8:67-68.
 It is narrated by:
- Ibn Ḥambal, Aḥmad, al-Musnad, 1:30 and 3:243.
- Abū Dāwūd, Kitāb al-sunan, Ḥadīth 2691.
- Al-Nasāʾī, al-Sunan al-kubrā, Ḥadīth 8661.
Shaykh Shuʿyab al-Arnauṭ classified it as a fair narration (ḥasan) in his revision of al-Musnad, whereas Ibn Qayyim al-Jawziyyah classifies it as sound (ṣaḥīḥ) in Zād al-maʿād fī hadyi khayr al-ʿibād.
 See Al-Zarkashī, al-Bahr al-muhīt, 4:1.
 It is narrated by:
- Al-Tirmidhī, al-Jāmiʿ al-kabīr, 4:466.
- Ibn Ḥambal, Aḥmad, al-Musnad, 6:396.
- Al-Ḥākim, al-Mustadrak ʿalā al-ṣaḥīḥayn, 1:201.
 For a more extensive read on the evidentiary authority of communal consensus from Canonic sources, see Shabbir, Yusuf, Dalāʾil hujjiyat al-ijmāʿ.
 In this report the Companion ʿUmar is apprehensive that his kissing, hence the intermingling of the external body that is saliva between mouths and its accidental swallowing might nullify his fast. But the Prophet (peace be upon him) makes an analogy to rinsing one’s mouth where there are remnants of water left in a person’s mouth and it is impractical, rather impossible to remove every particle of it. Therefore, if it is not a nullifying factor, kissing is also not a nullifying factor. This narration is reported by:
- Ibn Ḥambal, Aḥmad, al-Musnad, 1:21.
- Al-Dārimī, al-Sunan, 2:22.
- Abū Dāwūd, Kitāb al-sunan, Ḥadīth 2385.
 It is narrated by:
- Al-Ṭayālisī, Abū Dāwūd, al-Sunan, 1:286.
- Ibn Ḥambal, al-Musnad, ed. Shuʿayb al-Arnauṭ (Beirut: Muʾassasah al-Risālah, 2001), 36:333, 382, 417.
- Al-Tirmidhī, Ḥadīth 1327.
- Abū Dāwūd, al-Sunan, Ḥadīth 3585.
- Ibn ʿAbd al-Barr, Jāmiʿ bayān al-ʿilmi wa faḍlih, 2:55-56.
Certain scholars have considered this report to be weak because the narrators from Mu’ādh himself are unknown although it is a large number of them (the chain is from al-Ḥārith ibn ʿAmr–multiple unnamed sources from the students of Muʿādh–Muʿādh ibn Jabal–the Messenger (peace be upon him). Furthermore, al-Ḥārith also is a veiled narrator (majhūl). Despite that, numerous masters of Ḥadīth criticism have affirmed its substantiality such as Abū Bakr al-Jaṣṣāṣ al-Rāzī, Ibn al-ʿArabī, al-Khaṭīb al-Baghdādī, and Ibn Qayyim al-Jawziyyah (prominent scholars of each school of thought). Al-Khaṭīb states after narrating it in his celebrated work al-Faqīh wa-l-mutafaqqih: “Indeed, the scholars have accepted it and utilized it as evidence, we therefore acknowledged its authenticity… and if these reports are not established in terms of their chains, their collective transmission from numerous sources in every generation (talaqqī al-kāffah ʿan al-kāffah) suffices to establish their authenticity according to them (i.e. the scholars of Ḥadīth criticism).” See al-Baghdādī, Aḥmad ibn ʿAlī, al-Faqīh wa al-mutafaqqih, 1:189-90. Likewise, Ibn al-Qayyim states: “This is a Ḥadīth, albeit its transmission is from unnamed sources [in the link after Muʿādh], they are the disciples of Muʿādh. Therefore that is not detrimental to [the authenticity of] it, because it indicates the dissemination of the Ḥadīth. The narrator al-Hārith ibn ʿAmr relates it from a group of Muāʿdh’s disciples, not an individual from them; this is more emphatic of [its] dissemination (shuhrah) than the narration of one individual albeit named. And why not when the prominence of the disciples of Muʿādh in knowledge, piety, virtue, and truthfulness is of a status well-known?” See Ibn al-Jawzī, Iʿlām al-muwaqqiʿīn ʿan rabb al-ʿālamīn, 1:202.
 See al-Shīrāzī, Ṭabaqāt al-fuqahāʾ, 20.
 See Abū al-Ḥāj, Salāḥ, Masār al-wuṣūl ilā ʿilm al-uṣūl (Amman: Dār al-Fatḥ, 2017), 32-35.
 The loose report (al-ḥadīth al-mursal) was accepted by all the inaugurators of the schools of legal hermeneutics and earlier scholars such as Sufyān al-Thawrī, al-Awzāʿī, etc. except Imām al-Shāfiʿī (see Abū Dāwūd, Risālat al-imām Abī Dāwūd al-Sijistānī ilā ahl Makkah fī waṣfi sunanih, ed. ʿAbd al-Fattāḥ Abū Ghuddah, 32). There are opposing narrations concerning its acceptability from Imām Aḥmad, of which the more authentic and preferred narration is that of its acceptability (see Ibn Taymiyyah, ʿAbd al-Salām, ʿAbd al-Halīm & Aḥmad, al-Muswaddah fī uṣūl al-fiqh, 250 and Ibn al-Jawzī, al-Taḥqīq fī aḥādīth al-khilāf, 1:182, 188). Imām al-Shāfiʿī accepts the loose report provided certain conditions are found, which are mentioned in his al-Risālah (see al-Shāfiʿī, al-Risālah, ed. Aḥmad Shākir, (Cairo: Muṣṭafā al-Bābī al-Ḥalabī, 1940). On a detailed discussion concerning the acceptability of the loose report in the four schools, see al-Suyūṭī, Jalāl al-Dīn, Tadrīb al-rāwī fī sharḥ taqrīb al Nawāwī, ed. Muḥammad ʿAwwāmah, (Madinah: Dar al-Minhāj, 2016), 3:139-48.
 See Abū Dāwūd, Kitāb al-marāsīl, ed. Dr. ʿAbdullāh al-Zahrānī, (Riyadh: Dār al-Samīʿī, n.a.) and al-Zaylaʿī, Naṣb al-rāyah fi takhrīji aḥādīth al-hidāyah, 297-8.
 Imām Abū Ḥanīfah’s being one of the Successors has been accepted by mainstream scholars. The leading Shāfiʿite jurist Ibn Ḥajar al-Haytamī cited the biographical narrations of numerous scholars establishing his encountering the Companions (may Allah be pleased with them). He enumerated up to 16 Companions Imām Abū Ḥanīfah had seen, namely Anas ibn Mālik, Jābir ibn ʿAbdillāh, ʿAbdullah ibn al-Ḥārith ibn Jazʾ, etc. See al-Haythamī, al-Khayrāt al-ḥisān fī manāqib al-imām al-aʿẓam Abī Ḥanīfah al-Nuʿmān, (Cairo: Maṭbaʿah al-Saʿādah, n.a.). The late Turkish master in historical criticism Al-Kawtharī critically analyzed the possibility of Abū Ḥanīfah’s encounters with the Companions. He elucidates that there are three narrations as to the Imām’s year of birth; 61 AH, 70 AH, and 80 AH. Most scholars have assumed the last as it is the latest and safest in terms of establishing the connection of links in chains of narration. He then goes on to argue that opting the safest assumption is only done when such an indicator (qarīnah) is not found which gives superiority and preponderance to any of the narrations. In this case, there are indicators emphatically suggesting his birth was at an earlier time than 80 AH. In his book titled Mā rawāhu al-akābir ʿan Mālik or ‘[The Book Concerning] Those Narrations Transmitted by The Elders from Mālik’, Muḥammad ibn Makhlad al-ʿAṭṭār (d. 331 AH) included Prophetic narrations related by Ḥammād ibn Abī Ḥanīfah. Mālik’s era was 93 AH-179 AH, and Ḥammād was deceased in 176 AH, making his birth at the very least before 90 AH for him to be considered older than Mālik (thence the inclusion of his narrations in Ibn Makhlad’s treatise). If the Imām’s birth is considered to be in 80 AH, one is implicitly making an illation that he had a son at the age of 10, which is far-fetched. Al-Kawtharī then mentions two more indicators substantiating the narrations of an earlier date. Deducing his older age from these indicators, his year of birth being 61 AH or 70 AH makes it very likely that he met Anas ibn Mālik before his demise in 93 AH in the neighboring city of Basra. See for further details al-Kawtharī, Muḥammad Zāhid ibn al-Ḥasan, Taʾnīb al-Khaṭīb ʿalā mā sāqahū fī tarjumati Abī Ḥanīfata min al-akādhīb, (Cairo: n.a., 1990), 32-33, 40-44. This is merely required if one indulges in historical criticism. There are numerous scholars who have explicitly mentioned his encounter with Anas, such as Ibn Saʿd in his al-Ṭabaqāt, al-Dāraquṭnī, al-Khaṭīb al-Baghdādī in his Tārīkh Baghdād, Ibn ʿAbd al-Barr, al-Samʿānī, Ibn al-Jawzī, Imām al-Nawawī, Ḥāfiẓ al-Mizzī, the doyen of Prophetic sciences and history al-Dhahabī, al-Ṣafadī, Ibn Kathīr al-Dimashqī, al-Bulqīnī, al-ʿIrāqī, al-Jazarī, the behemoth and leader of the believers in Prophetic narrations Ibn Ḥajar, al-Suyūṭī, etc. Anyone with the least acquaintance in Islamic academia will acknowledge the caliber of the aforementioned scholars, surpassing sufficiency in satisfying the urge to ascertain whether the Imām was a Successor or not. See for detailed references the invaluable article authored by Ml. Yusuf Shabbir at https://nawadir.org/2016/10/12/was-imam-abu-hanifah-a-tabii/.
 Concerning his proficiency in dialectical sciences, an incident is reported by Imām al-Shāfiʿī. He relates: “[Imām] Mālik was asked ‘Have you encountered [Imām] Abū Ḥanīfah?’ He replied ‘Yes, I have seen such a man that if he spoke to you concerning this pillar, claiming it is made of gold, he would successfully prove it.’” Al-Dhahabī, Shams al-Dīn, Siyar aʿlām al-nubalā, ed. Shuaʿyb al-Arnauṭ and Ḥusayn al-Asad, (Beirut: Muʾassasah al-Risālah, 1982), 6:399.
 A triadic narration is a narration that has only three medial transmitters between the narrator and the Prophet (peace be upon him).
 Aḥādīth is the plural form of ḥadīth in Arabic.
 Ibn Abī al-ʿAwwām, Manāqib Abī Ḥanīfah wa akhbāruhū wa ḥayātuh.
 Al-Ḥākim al-Nisāpūrī, al-Madkhal ilā maʿrifati kitāb al-iklīl, ed. Aḥmad al-Salūm, (Beirut: Dār Ibn Hazm, 2002), 118.
 Ibn ʿAbd al-Barr, al-Intiqāʾ fī faḍāʾil al-aʾimmah al-thalāthah al-fuqahāʾ, ed. ʾAbd al-Fattāḥ Abū Ghuddah, (Beirut: Dār al-Bashāʾir al-Islāmiyyah, 1997), 257.
 Al-Baghdādī, al-Khaṭīb, Tārīkh Baghdād, ed. Bashshār ʿAwwād Maʿrūf, (Beirut: Dār al-Gharb al-Islāmī. 2001), 2:567-570.
 See al-Nuʿmānī, Abdul Rashīd, Makānat al-imām Abī Ḥanīfah fi al-Ḥadīth, ed. ʿAbdul Fattāḥ Abū Ghuddah, (Beirut: Dār al-Bashāʾir al-Islāmiyyah, 2007), 68-80.
 The general chain of legal scholarship of the Ḥanafite school is Abū Ḥanīfah–Ḥammād ibn Abī Sulaymān–Ibrāhīm al-Nakhaʿī–ʿAlqamah ibn Qays–ʿAbdullah ibn Mas’ūd (may Allah be pleased with all of them).
 This narration should not be misconstrued as a specification to the legal principles in the Ḥanafite school, because our discourse is on legal principles in general, be it any school. Abū Yūsuf was of an earlier era than any of the founders of the other schools, rather some were students of his students. This passage can be misleading for many readers, as it has been for the many that have authored in the history of legal theory. The lexeme uṣūl utilized is generally understood in legal context in later era as “legal theory” or “principles of law”, but in earlier eras, it was utilized to denote Islamic law. It was fathomed as the principles governing Islam in general, which in turn are the laws of Islam.
 See al-Samʿānī, al-Ansāb, ed. Muḥammad ʿAbdul Qādir ʿAṭā, (Beirut: Dār al-Kutub al-ʿIlmiyyah, 1998), 4:413 and Ibn Khallakān, Wafayāt al-aʿyān, ed. Iḥsān ʿAbbās, (Beirut: Dār Ṣādir, n.a.), 6:382.