A law that was not written down. The cumstoms were so firmly established that they had acquired obligatiory force. The recognition of a custom was however not an exact science and jurists debated whether the custom could be called a law or a binding.
Roman law was almost entirely customary in origin.
Royal decrees
The decree of the Kings had a direct binding force as law. Republic The twelve tables 451 BC
Ten men were appointed to study the laws of the Greek city states. The laws were written on wooden tablets. Then they discovered a deficiency in the first ten tables so they added two tables to the original set.
The twelve tables were the first legal text. Overall the Twelve Tables were probably based on existing customary law of Rome, but with some royal decrees and a few innovations added. The contant is broadly classified as consisting of public and private law. Romans considered the TT as the foundation of their civil law.
The twelve tables prepared by the patritians as the law they were willing to share with plebeians, in response to the plebeians request for equal rights of liberty.
Assemblies
Untill the republic there were only a handful of statutory changes. The most important one regards private law, was the lex aquilia which reformed the law on wrongful damage to property.
The assemblies could not initiate legislation, they met to vote on proposals drawn up in a draft bill that normally would have been debated in the Senate. The task was to accept or reject the bill, not debate.
Comitia centuriata was the most important of the assemblies. It elected high-ranking magistrates and was organized the Roman people in military array.
Comitia curiata was the oldest assembly but had a minor role in legislation, its main function being formally to confer powers on superior magistrates.
Comitia tribute was based on a geographical division of the populace into tribes, handled routine