The two chief sources of Hindu law are the Shruti, i.e. the Vedas, more particularly the Brahmanas, which contain the main body of law, and the Smriti, especially the dharma-shastras or law books. Various rules have been laid down by law givers. Smriti is a law manual. The whole body of sacred tradition or what is remembered by human teachers heard or revealed to the Rishis; in its widest acceptation this use of the term smriti includes the six vedangas; the sutras both shrauta and grihya; the law books of manu; the itihasa (e.g. Mahabharata and Ramayana, the Puranas and the Nitishastras). The whole body of codes of law as handed down by tradition (especially the codes of Manu, Yajnavalkya and the 16 succeeding inspired lawgivers such as Atri, Vishnu, Harita, Vshanas or Shukra, Angiras, Yama, Apastamba, Samvrata, Katyayana, Brihaspati, Parashara, Vyasa, Shankha, Likhita, Daksha and Gautama); all these lawgivers being held to be inspired and to have based their precepts on the veda.
Katyayana occupies a very prominent place among Smriti writers on law and procedure. Next to Narada and Brihaspati he is cited on Vyavahara more frequently than any other Smritikara in such commentaries and digests as the Mitakshara, the smritichandrika, the Viramitrodaya and the Vyavaharamayukha. In Katyayana's work over nine hundred quotations have been collected. He has a great penchant for distinctions and gives numerous definitions, such as those of Vyavahara, Pradvivaka, Stobhaka, Samanta, Maula, Vriddha etc. he gives a more elaborate treatment of vidyadhana than is contained in any other Smritikara.
The Vishnu Smriti or Vaishnava Dharmashastra or Vishnu sutra is the main collection of ancient aphorisms on the sacred laws of India.
The Naradiya Dharamashastra or Narada Smriti like most of the Smritis or ancient codes of revealed law of the Hindus, is called by the name of an ancient rishi.
Manu called the lawgiver, the supposed author of a famous code of Hindu law and Jurisprudence. The code of Manu is known variously as the Manu-Smriti, the Manava Dharma-shastra or the Manu-samhita.
The code is fundamentally a handbook of Hindu jurisprudence, the first systematic treatment of Hindu law, and the precursor of all other dharmashastras or brahminical legal manuals. Brahmins regard it as the most important work after the Vedas and shrautasutras. The code lays down social, moral and ethical precepts for the guidance of the people and formulates rules for the observance of rites and ceremonies. It is held to be absolutely binding on Hindus. A famous vedic verse declares "All that Manu said is medicine", a reference to the mythological manu, although taken as applying to the Manu of the code. A Smriti (law manual) opposed to Manu was not approved.
Book I of Manu's code is cosmological in content and gives a semi-philosophical account of creation; Book II gives the sources of law, and describes the first of the ashramas (stages of life) i.e. that of a brahmachari or student, and summarizes his duties; Book III describes the life of the second of the ashramas, the grihastha or householder, with reference to his marriage, daily rites, funeral offerings. Book IV treats of the various occupations and general rules of life for the householder; Book V lays down rules concerning women, and dietary obligations such as lawful and forbidden foods; Book VI gives rules about the next two stages of life, namely vanaprastha and sannyasin; Book VII discusses the sources of law, general political maxims and the duties of kings. Among other things the code advocates sowing dissension among enemies, fomenting intrigues in the courts of neighbouring kings and the employment of spies; Book VIII relates to civil and criminal law, procedure, evidence, debts, ownership; Book IX relates to domestic law, the rules governing women (generally to their detriment), husbands, and marriage; parents and children, inheritance, deaths, funerals; Book X is about the origin, development and rules of caste; also rules for vaishyas, sudras and mixed castes, and caste occupations; Book XI deals with the general laws of morality, the nature of good and evil; gifts and sacrifices; the patakas or sins; penance and expiation for sins, particularly sins against caste; Book XII describes the future consequences of good and bad action, the nature of the soul, the path of liberation and the means of attaining release, the doctrine of transmigration.