Abu Hanifa notoriously used istihsan (juristic preference) to make seemingly subjective rulings. In response, al-Shafii declared istihsan invalid. Later Hanafis retorted that al-Shafii had misunderstood the term. Western scholars similarly disagree on its definition. To resolve this debate, and to understand the role of subjective reasoning in early Iraqi law, this paper presents an empirical dataset of every istihsan ruling (approx. 500) in the Kitab al-Asl of Muhammad al-Shaybani. In so doing, the paper strives to correct a few critical misconceptions about istihsan. Firstly, the paper shows that, despite istihsan’s stereotypical association with lenience, it only connotes lenience in a minority of cases, often functioning instead to make the law more stringent. This insight, coupled with the paper’s articulation of the diverse justifications (approx. 60) that might underlie an istihsan ruling, shows that it was not just a mechanism for ease, but allowed jurists to intervene when the law clashed with their moral or social sensibilities. Secondly, the paper reveals quantifiable differences in how early Iraqi jurists used istihsan, with Abu Hanifa utilizing it most subjectively, followed by Abu Yusuf, followed by al-Shaybani. This confirms the conventional narrative of early Hanafi doctrine aspiring to become more textual, and allows us to track that development in concrete terms by observing how discrete types of reasoning became more or less favored over time. Finally, the paper places these findings within the context of 9th century Iraqi legal theory, showing how this reframing of istihsan sheds light on many puzzles of the formative period, including early Iraqi responses to al-Shafii, as well as the state of legal theory before usul al-fiqh. Indeed, research on the theoretical battles over istihsan in the 9th century reveals an immature Basran line of legal theory (led by figures like al-Jahiz and Muways b. Imran) that openly embraced the subjectivity inherent to istihsan, and whose successors attempted to make logical, theological, and textual proofs for why jurists have the authority to make law without evidence. Needless to say, these radical arguments did not survive into classical usul. In short, this paper tells the story of istihsan, and in so doing, tells a broader story about the rise of an Islamic legal orthodoxy that aspired to objective legal reasoning.