Sources of Roman law:

1. Leges regiae (The law of the King)
2. Customs of Antiquity 
3. Legislation. 
 There were four legislative body in ancient Rome. Such as
 (a) Comitia Curiata
 (b) Comitia Centuriata
 (c) Comitia Tributa
 (d) Concilium Plebis

4. Practorian edicts (Decision of the megistrates) 
5. Responsa prudentium (Opinion of the jurists)
6. Senatus consulta (The consultation of senate)
7. Corpus Juris Civilis (Justinian's Codification )
8. Imperial Constitutions. 
9. Twelve table