This book is one of the "Ḍarūrīyyāt", that are a group of abridgments written by ibn Rušd, including "al-Ḍarūrī fī al-Manṭiq", "al-Ḍarūrī fī al-Naḥw", "al-Ḍarūrī fī al-Siyāsa" that is an abridgment o This book is one of the "Ḍarūrīyyāt", that are a group of abridgments written by ibn Rušd, including "al-Ḍarūrī fī al-Manṭiq", "al-Ḍarūrī fī al-Naḥw", "al-Ḍarūrī fī al-Siyāsa" that is an abridgment of Plato's Republic, and this book; "al-Ḍarūrī fī Uṣūl al-fiqh" that is an abridgments of al-Ġazālī's al-Mustaṣfā. Ibn Rušd does not explicitly name the book, but it was, however, given that name based on the comparison to the other works holding the same name. This is most probably the reason that many sources did not mention that book for ibn Rušd. Ibn Rušd starts the book by an introduction in which he divides the types of knowledge, decides the place of uṣūl al-fiqh (principles of jurisprudence) among them, and explains his plan for the book. The book consists of four chapters. In the first chapter, he discusses the nature of the legal verdicts itself: its definition, types, and mandatory components. The second chapter covers the principles of jurisprudence as listed by al-Ġazālī: The Book (the Quran), the tradition of the prophet (the Sunna), the consensus of the Muslim community, and the rational evidence of the validity of matters that no text forbids. However, ibn Rušd does not agree with al-Ġazālī that such rational evidence should be counted among the "principles" as it does not provide a positive proof as much as it only proves the absence of the evidence. Ibn Rušd believes that the only reason that the jurists listed such an negative evidence among the "principles" is their exaggeration in demanding a textual evidence to judge any matter. In the third chapter, ibn Rušd concludes al-Ġazālī's chapter on the tools that produces the legal verdicts from its principles. In the last chapter, he discusses the requirements of a jurist to be considered a "mujtahid."

كتاب جمع فيه المؤلف أهم اﻷصول التي كُتبت قبله من أمثال كتاب" البرهان" للجويني، و"المستصفى" للغزالي، و"العهد" للقاضي عبد الجبار، و"المعتمد" ﻷبي الحسين البصري، بعد أن أضاف اليها الكثير من آراءه الفقهية كتاب جمع فيه المؤلف أهم اﻷصول التي كُتبت قبله من أمثال كتاب" البرهان" للجويني، و"المستصفى" للغزالي، و"العهد" للقاضي عبد الجبار، و"المعتمد" ﻷبي الحسين البصري، بعد أن أضاف اليها الكثير من آراءه الفقهية واﻷصولية. والكتاب مقسم إلى عدة أقسام كبيرة. احتوى القسم اﻷول على مقدمات فى التعريف بعلم أصول الفقه وموضوعه، والحكم الشرعي وأقسامه. القسم الثاني تناول فيه الكلام عن اللغات وأحكامها الكلية وتقسيم اﻷلفاظ وأحكام الترادف والتوكيد والحقيقة والمجاز، الخ. تم تكلم في بقية اﻷقسام عن اﻷوامر والنواهي والعموم والخصوص والناسخ والمنسوخ. كما تناول اﻷدلة الشرعية من قرآن وسنة واجماع وقياس، الخ. وفي النهاية تكلم عن الاجتهاد وحكمه، والفتوى وصفات المفتي والمستفتي.